N64 Bowser's Castle

Bowser's Castle is a race course in Mario Kart 64 and features Thwomps that block drivers from preceding to further areas. Near the beginning of the course, there is a green Thwomp locked in a cage with yellow teeth, who will shake and laugh if the player goes near it. This laugh can also be heard by the normal Thwomps throughout the course. In further corridors there are pictures of Bowser and large stone statues that shoot flames from their mouths, but they are harmless. At the end of the track racers will race on the roof of the castle. On the last lap, or when the player gets too close to the Bowser statue at the start of the track, Bowser's famed laugh plays. Thwomps are the main obstacle in this course. Most of them will move around the room and try to crush the racers, some are stationary, and some slide across the room. It is the second Bowser's Castle not to be in Special Cup, following Bowser's Castle 3 from Super Mario Kart. The Bowser's Castles in later Mario Karts are all in the Special Cup.

This course reappears as the fourth and last course of the Lightning Cup in Mario Kart Wii. Many changes have been made. In this version, lava columns spring out from the pits to cause the drivers to bowl over, specially when racers attempt to jump. The green Thwomp present in the Nintendo 64 version is no longer there, instead it is replaced by a normal thwomp that looks no different then the rest, however it will shake and make an angry expression when a player comes near, and also laugh. The flame-shooting statues are still harmless. Bowser's laugh is still heard on entry on the final lap, or when the player gets too close to the Bowser statue at the start of the track. It is the longest track, taking around one minute per lap, and one of the most difficult tracks in the game.

Instruction manual description
''Surprisingly, the Bowser's Castle has been transformed into a race ground! Because it's inside the building, most of the corners are tricky right angles. However, the most difficult part of the course is where the Thwomps are. They will block your path, and if you run into one, you will spin out. Should you be stepped by one, you'll find yourself squished flat as a pancake.''

Tournaments
In Mario Kart Wii, a tournament occurred on this track, which had players race against Dry Bowser, who utilized the ability to attack with fireballs. This tournament took place as the second tournament for March 2009, and it was restricted to karts. It was later repeated as the second tournament of June 2010, but without any restrictions. It was repeated for the third time as March 2011's second tournament, and the karts only restriction returned.

Trivia

 * The Thwomps' laugh is the same as Wario's only pitched down. Due to the voice change for some of the characters in the international release the Thwomps' voices changed with them.
 * The Bowser statue at the start of N64 Bowser Castle's eyes will light up while Bowser's laugh is playing. But Kenny James replaced the voice of him in Mario Kart Wii using the actual voice of Bowser.