- For the level in Bloons Junior, see Castle (Bloons Junior Level).
- For the track in Bloons Tower Defense 6 , see Dark Castle.
In the palace kingdom, the water here forms in a moat. Castle is a very hard track compared to other Expert Tracks that tests your ability to stop two alternating streams of Bloons. It travels two paths and merges into one. It appears also in the Fast Upgrades Special Mission where it is required to pass five special rounds to complete.
Much of the space in the center of the castle can be used as open space, useful for Mortar Towers or Banana Farms.
|Castle Co-Op Olympian||75|
- Main article: Castle/Strategies
- Up to 42 Monkey Buccaneers can be placed on water.
- If the player pops a M.O.A.B. Class Bloon quickly (i.e. as soon as they are seen), the MOABs/Ceramic Bloons will take separate paths (two on each path).
- There is a Sun God symbol at the middle of the castle.
- This map is arguably one of the hardest in the BTD series because it has two paths that are far away from each other & the merge is right next to the exit.
- This track is bridge to bridge because the entrance has a bridge and the another, too.
- There are 2 coloured flags: Red and Blue. It's noticeable that they can't wave; they're just steady.
- In mobile, the flag does wave.
- Although it looks like there are 2 entrances, there is actually 1 path that splits at the start.
- This track has a slightly harder Halloween variant, Spooky Castle.