The Castle is a Structure that allows for Monsters to be placed on an Island - each castle provides a certain number of beds for monsters. Aside from Gold Island, Wublin Island, Tribal Island, Celestial Island, Composer Island, and The Colossingum, each island starts with the same Basic Castle and the progression through the castles is the same, with the same number of beds for each level of castle (the number of beds per castle is increased on Ethereal Island, due to the fact that Ethereal Monsters occupy large numbers of beds), but the time and cost required and Experience granted for each upgrade differs based on the island. Gold Island has a single castle - the Crystal Castle - which does not have a bed limit, and cannot be upgraded. Composer Island also has a single special Castle, and every monster takes up one bed, except Glowbes, which take up no beds.
There are two mini-games that you can play from the Castle.
In the following table, the number of beds shown is given as the number on all islands except Ethereal, followed by a slash and the number of beds on Ethereal Island.
Castle Image
Castle
Beds
Basic Castle
“
Singing takes a lot of energy, and monsters need sleep! The Basic Castle really isn't very comfy at all; the rain gets through, it's drafty, and cramped.
”
4/20
Modest Castle
“
It's great to have a good night's sleep! The Modest Castle is dry and warm, but small.
”
10/45
Comfortable Castle
“
Ah, some elbow room! The Comfortable Castle even has indoor plumbing.
”
18/80
Spacious Castle
“
The Spacious Castle has lots of room for monsters to relax and refresh.
”
28/125
Luxurious Castle
“
It just doesn't get any better than this! The Luxurious Castle has everything a monster might enjoy, from cold slime pools to dark, nasty dungeons. Who would ever want to leave?
”
40/175
Extravagant Castle
“
This state of the art domicile goes way overboard when it comes to spoiling the monsters... Personal assistants to wait on them hand and foot (at least those that have hands and feet), the spiffiest sound systems on the monster market... They've got it made in the shade.
”
60/265
Paradise Castle
“
After agreeing that more beds equals more fun, the monsters set out to create the most capacious castle ever - and what better inspiration than Gold Island's own Crystal Castle? Following extensive study of the original architectural marvel, the multiverse's finest architects were tapped to craft the new castle in its image. After the smoke cleared, there was no question - this is the be-all and end-all of monster living arrangements. Welcome to paradise!
”
90/400
Crystalline Castles
Crystalline Castle upgrades were added in the 2.4.1. update and are only available on the Natural Islands. These upgrades allow at least one of each monster to be on the island at once, with the maximum bed space at the final upgrade being 180. Each castle is unique, sporting the color and features of the island, as well as the element it represents. The descriptions of the castles state that they were built using the crystals from the Dawn of Fire (when the islands were simply the elemental lands of the Continent), and said crystals are visible on the top pillars. Each castle has the crystal from the elemental land the island represents: Plant Island’s Crystalline Castle has Vegidian crystals, Cold Island’s has Frozium, and so on. There are three natural crystals on the first Crystalline Castle upgrade, with two polished crystals being added on the second, and one carved crystal on the third. Each island’s crystalline castle costs 20 more diamonds than the previous island’s castle. To upgrade the Crystalline Castle further, it will cost 80 more diamonds than level 1 for the second level and 160 more than that for the third. (Plant Island’s castle takes 80 diamonds for level 1, 160 for level 2, and 320 for level 3. Cold Island’s take 100 diamonds for level 1, 180 for level 2, and 340 for level 3. This keeps going up throughout the islands.)
Castle Image
Castle
Beds
Plant Island
Vegidian Castle
“
Thanks to mineralogical acumen supplied by Fire Monsters, Plant Island's residents knew exactly where to dig to find vast deposits of Vegidian, a crystal once found in abundance back when the island was an Elemental Land of the prehistoric Continent. Combining the raw strength of the crystal with modern lapidarian techniques has resulted in this magnificent Castle, furnished with more Beds than ever before.
”
120
Polished Vegidian Castle
Description is the same as Vegidian Castle
150
Carved Vegidian Castle
Description is the same as Vegidian Castle
180
Cold Island
Frozium Castle
“
Thanks to mineralogical acumen supplied by Fire Monsters, Cold Island's residents knew exactly where to dig to find vast deposits of Frozium, a crystal once found in abundance back when the island was an Elemental Land of the prehistoric Continent. Combining the raw strength of the crystal with modern lapidarian techniques has resulted in this magnificent Castle, furnished with more Beds than ever before.
”
120
Polished Frozium Castle
Description is the same as Frozium Castle
150
Carved Frozium Castle
Description is the same as Frozium Castle
180
Air Island
Skylite Castle
“
Thanks to mineralogical acumen supplied by Fire Monsters, Air Island's residents knew exactly where to dig to find vast deposits of Skylite, a crystal once found in abundance back when the island was an Elemental Land of the prehistoric Continent. Combining the raw strength of the crystal with modern lapidarian techniques has resulted in this magnificent Castle, furnished with more Beds than ever before.
”
120
Polished Skylite Castle
Description is the same as Skylite Castle
150
Carved Skylite Castle
Description is the same as Skylite Castle
180
Water Island
Aquanine Castle
“
Thanks to mineralogical acumen supplied by Fire Monsters, Water Island's residents knew exactly where to dig to find vast deposits of Aquanine, a crystal once found in abundance back when the island was an Elemental Land of the prehistoric Continent. Combining the raw strength of the crystal with modern lapidarian techniques has resulted in this magnificent Castle, furnished with more Beds than ever before.
”
120
Polished Aquanine Castle
Description is the same as Aquanine Castle
150
Carved Aquanine Castle
Description is the same as Aquanine Castle
180
Earth Island
Stonyx Castle
“
Thanks to mineralogical acumen supplied by Fire Monsters, Earth Island's residents knew exactly where to dig to find vast deposits of Stonyx, a crystal once found in abundance back when the island was an Elemental Land of the prehistoric Continent. Combining the raw strength of the crystal with modern lapidarian techniques has resulted in this magnificent Castle, furnished with more Beds than ever before.
”
120
Polished Stonyx Castle
Description is the same as Stonyx Castle
150
Carved Stonyx Castle
Description is the same as Stonyx Castle
180
Other Castles
Some Islands' Castles cannot be upgraded and are already at maximum.
These castles are exclusiveto one island each.
Castle Image
Castle
Beds
Gold Island
Crystal Castle
“
Although shaped like a castle, this mysterious structure actually serves as the main power generator in the monster dimension of the multiverse! It's from here that monsters derive their musical inspiration, as well as their tireless energy so that they can keep singing forever!
”
Unlimited
Composer Island
Composer Castle
“
The Castle on Composer Island is styled after another famous Structure in the Monster World, but the similarity is more than skin deep! Just as the Crystal Castle serves as a power generator for Gold Island, the Composer Castle acts as a powerful transmitter for the creative energies flowing in from the human universe - it's got some of the Seam's best upload/download speeds!
”
Note: Monsters on Composer Island only take up 1 Bed except the Glowbe, meaning a total of 40 Monsters can be placed, while Glowbes can be placed as long as there is physical space on the island.
40*
Upgrade costs
Cost and time to upgrade the Castle varies by Island.
Plant Island
Castle
Cost
Time
XP
Beds
Modest Castle
500
20 seconds
375
10
Comfortable Castle
3,000
1 hour
750
18
Spacious Castle
15,000
4 hours
3,750
28
Luxurious Castle
30,000
6 hours
7,500
40
Extravagant Castle
20
8 hours, 20 minutes
14,000
60
Paradise Castle
40
16 hours
28,000
90
Vegidian Castle
80
1 day
56,000
120
Polished Vegidian Castle
160
1 day, 8 hours
112,000
150
Carved Vegidian Castle
320
1 day, 16 hours
224,000
180
Cold Island
Castle
Cost
Time
XP
Beds
Modest Castle
50,000
8 hours
12,500
10
Comfortable Castle
100,000
10 hours
25,000
18
Spacious Castle
250,000
12 hours
62,500
28
Luxurious Castle
500,000
14 hours
125,000
40
Extravagant Castle
25
8 hours, 20 minutes
14,000
60
Paradise Castle
50
16 hours
28,000
90
Frozium Castle
100
1 day
56,000
120
Polished Frozium Castle
200
1 day, 8 hours
112,000
150
Carved Frozium Castle
400
1 day, 16 hours
224,000
180
Air Island
Castle
Cost
Time
XP
Beds
Modest Castle
100,000
16 hours
250,000
10
Comfortable Castle
400,000
18 hours
375,000
18
Spacious Castle
1,200,000
20 hours
625,000
28
Luxurious Castle
2,400,000
22 hours
1,000,000
40
Extravagant Castle
30
8 hours, 20 minutes
14,000
60
Paradise Castle
60
16 hours
28,000
90
Skylite Castle
120
1 day
56,000
120
Polished Skylite Castle
240
1 day, 8 hours
112,000
150
Carved Skylite Castle
480
1 day, 16 hours
224,000
180
Water Island
Castle
Cost
Time
XP
Beds
Modest Castle
250,000
24 hours
1,625,000
10
Comfortable Castle
1,000,000
26 hours
1,875,000
18
Spacious Castle
3,000,000
28 hours
2,125,000
28
Luxurious Castle
6,000,000
30 hours
2,312,500
40
Extravagant Castle
35
8 hours, 20 minutes
14,000
60
Paradise Castle
70
16 hours
28,000
90
Aquanine Castle
140
1 day
56,000
120
Polished Aquanine Castle
280
1 day, 8 hours
112,000
150
Carved Aquanine Castle
560
1 day, 16 hours
224,000
180
Earth Island
Castle
Cost
Time
XP
Beds
Modest Castle
750,000
32 hours
2,937,500
10
Comfortable Castle
2,250,000
34 hours
3,312,500
18
Spacious Castle
4,500,000
36 hours
3,750,000
28
Luxurious Castle
6,750,000
48 hours
4,187,500
40
Extravagant Castle
40
8 hours, 20 minutes
14,000
60
Paradise Castle
80
16 hours
28,000
90
Stonyx Castle
160
1 day
56,000
120
Polished Stonyx Castle
320
1 day, 8 hours
112,000
150
Carved Stonyx Castle
640
1 day, 16 hours
224,000
180
Fire Haven
Castle
Cost
Time
XP
Beds
Modest Castle
1,000,000
16 hours
250,000
10
Comfortable Castle
3,000,000
18 hours
375,000
18
Spacious Castle
6,000,000
20 hours
625,000
28
Luxurious Castle
9,000,000
22 hours
1,000,000
40
Extravagant Castle
30
8 hours, 20 minutes
14,000
60
Paradise Castle
60
16 hours
28,000
90
Fire Oasis
Castle
Cost
Time
XP
Beds
Modest Castle
1,500,000
16 hours
250,000
10
Comfortable Castle
4,500,000
18 hours
375,000
18
Spacious Castle
9,000,000
20 hours
625,000
28
Luxurious Castle
13,500,000
22 hours
1,000,000
40
Extravagant Castle
32
8 hours, 20 minutes
14,000
60
Paradise Castle
64
16 hours
28,000
90
Light Island
Castle
Cost
Time
XP
Beds
Modest Castle
1,625,000
24 hours
1,625,000
10
Comfortable Castle
4,875,000
26 hours
1,875,000
18
Spacious Castle
9,750,000
28 hours
2,125,000
28
Luxurious Castle
14,625,000
30 hours
2,312,500
40
Extravagant Castle
34
8 hours, 20 minutes
14,000
60
Paradise Castle
68
16 hours
28,000
90
Psychic Island
Castle
Cost
Time
XP
Beds
Modest Castle
1,750,000
24 hours
1,625,000
10
Comfortable Castle
5,250,000
26 hours
1,875,000
18
Spacious Castle
10,500,000
28 hours
2,125,000
28
Luxurious Castle
15,750,000
30 hours
2,312,500
40
Extravagant Castle
36
8 hours, 20 minutes
14,000
60
Paradise Castle
72
16 hours
28,000
90
Faerie Island
Castle
Cost
Time
XP
Beds
Modest Castle
1,875,000
24 hours
1,625,000
10
Comfortable Castle
5,625,000
26 hours
1,875,000
18
Spacious Castle
11,250,000
28 hours
2,125,000
28
Luxurious Castle
16,875,000
30 hours
2,312,500
40
Extravagant Castle
38
8 hours, 20 minutes
14,000
60
Paradise Castle
76
16 hours
28,000
90
Bone Island
Castle
Cost
Time
XP
Beds
Modest Castle
2,000,000
24 hours
1,625,000
10
Comfortable Castle
6,000,000
26 hours
1,875,000
18
Spacious Castle
12,000,000
28 hours
2,125,000
28
Luxurious Castle
18,000,000
30 hours
2,312,500
40
Extravagant Castle
40
8 hours, 20 minutes
14,000
60
Paradise Castle
80
16 hours
28,000
90
Shugabush Island
Castle
Cost
Time
XP
Beds
Modest Castle
50,000
8 hours
12,500
10
Comfortable Castle
100,000
10 hours
25,000
18
Spacious Castle
250,000
12 hours
62,000
28
Luxurious Castle
500,000
14 hours
125,000
40
Extravagant Castle
30
8 hours, 20 minutes
14,000
60
Paradise Castle
60
16 hours
28,000
90
Seasonal Shanty
Castle
Cost
Time
XP
Beds
Modest Castle
50,000
8 hours
12,500
10
Comfortable Castle
100,000
10 hours
25,000
18
Spacious Castle
250,000
12 hours
62,000
28
Luxurious Castle
500,000
14 hours
125,000
40
Extravagant Castle
30
8 hours, 20 minutes
14,000
60
Paradise Castle
60
16 hours
28,000
90
Ethereal Island
Castle
Cost
Time
XP
Beds
Modest Castle
525
12 hours
375
45
Comfortable Castle
800
14 hours
750
80
Spacious Castle
1,375
16 hours
3750
125
Luxurious Castle
2,250
18 hours
7500
175
Extravagant Castle
30
8 hours, 20 minutes
14000
265
Paradise Castle
60
16 hours
28,000
400
Magical Sanctum
Castle
Cost
Time
XP
Beds
Modest Castle
525
8 hours
375
10
Comfortable Castle
800
10 hours
750
18
Spacious Castle
1,375
12 hours
3750
28
Luxurious Castle
2,250
14 hours
7500
40
Extravagant Castle
30
8 hours, 20 minutes
14000
60
Paradise Castle
60
16 hours
28,000
90
Castle and Hotel Beds
The number of Monsters you can place on the Island depends on how many Beds they take up, and how many Beds are available in the Castle.
A further number of Monsters may be placed in the optional Hotel Structure, with its own limit on number of Beds.
When you attempt to place a Monster from the Nursery Structure onto the Island, but there aren't enough Beds available in the Castle, you may receive one of the following messages:
If you do not have a Hotel, and...
your Castle is not fully upgraded: "Your Castle does not have enough Beds. Go to Castle to upgrade now?" This is accompanied with a button that causes the Castle to be selected so you can easily upgrade it.
your Castle is fully upgraded: "Your Castle is fully upgraded and does not have enough Beds.". This means you will be unable to place the Monster on the Island without either constructing a Hotel first, or removing enough Monsters from the Island to free up the number of Beds required.
If you do have a Hotel, and it has enough Beds available, and...
your Castle is not fully upgraded: "Your Castle does not have enough Beds. You can go to the Castle to upgrade it or check in to the Hotel." This provides two buttons: One to go and upgrade your Castle, and the other allowing you to check the Monster straight into the Hotel without the need to place it on the Island first.
your Castle is fully upgraded: "Your Castle is fully upgraded and does not have enough Beds. Check in to Hotel?", which provides only the button to check the Monster straight into the Hotel.
If you do have a Hotel, but it does not have enough Beds available, and...
your Castle is not fully upgraded: "Your Castle does not have enough Beds and your Hotel is full. Go to Castle to upgrade now?", which only lets you go to the Castle to upgrade it.
your Castle is fully upgraded: "Your fully upgraded Castle does not have enough Beds and your Hotel is full." This means you will be unable to place the Monster on the Island, nor check it into the Hotel, requiring you to remove enough Monsters from the Island to free up the number of Beds required
Note that this game mechanic, introduced in version 2.4.1, does not provide a button to go upgrade your Hotel, if your Hotel does not have enough Beds available but could be upgraded, nor does it suggest Buying a Hotel if you do not have one (but could Buy one, requiring Level 15).
It also does not check if your Island has enough physical space (see Island Grid Planning) for the Monster to be placed, which means that if you have enough Beds on the Island and enough Beds in the Hotel, but there's no free space on the Island to actually fit the Monster, you will not be shown the option to place it in the Hotel instead; you will have to make space on the Island.
Notes
When first introduced, the Extravagant Castle had a maximum of 52 beds. However with the update to version 1.1.3, the maximum beds was increased to 60.
The castle on Shugabush Island does not produce any bass sound. Instead, Shugabass produce a bass sound.
The Vita version of the game currently does not include the Paradise Castle. However, the Big Fish version does.
For a long time, there was a hint of a new castle being added. The hint could be viewed from the log-on screen hints and tips. It said, "The Extravagant Castle is the Maximum Castle. For now." This hint has now been realized in the Paradise Castle.
1/2
Costs for Extravagant and Paradise Castles in Water and Earth Islands increased after the Anniversary Month Celebration ended in 2014. Instead of each of the Extravagant Castles costing 30 , they now cost 35 in Water Island and 40 in Earth Island. The Paradise Castles cost 70 and 80 respectively.
The castle on Ethereal Island has more beds than the natural islands, due to the fact that Ethereal monsters take up more beds than usual.
The castle on Composer Island is a Paradise Castle with only 40 beds. However, all monsters on Composer Island except the Glowbe occupy one bed. (Glowbes occupy zero beds.)
Although the game states that Monsters sleep in the castle, they do not go to sleep by themselves, and when muted do not go into the castle.
The Castle on Psychic Island was the only non-upgraded Castle to play sound. It was confirmed by the Monster-Handlers to be a bug and was later fixed.
The Crystalline Castles were added to the game on June 3rd, 2020. They are based off of the Crystals from Dawn of Fire. The Crystalline Castles are likely not called Crystal Castles to avoid confusion with Gold Island’s Crystal Castle.
Upgrading to a Crystalline Castle presents a warning reading "Warning: Using the maximum number of Beds in the next Castle upgrade may result in some sound and performance issues on older devices. Continue?"
Prior to Update 2.4.1, Composer Island’s castle was just a Paradise Castle. However, this was changed in the update, probably to not confuse players.
When boxing a monster on Gold Island, the Bed count of the monster's original island will not update until you return there.
, they now cost 35 
