Pendulum Castle is the eighth level of Superstar Road in New Super Mario Bros. U. It is unlocked when the player collects every Star Coin in Peach's Castle. This is one of the two castle levels in the game with no boss, the other being Red-Hot Elevator Ride.
Pendulum Castle is used for two challenges in the game. The first is Castle Crawl, which challenges the player to complete the level without being able to run. The second is Cashless Castle Crawl, which is the same challenge, but also requiring the player to beat the level collecting less than six coins.
The course is based off of the castle levels throughout the game, specifically The Final Battle. The level begins next to a large Ball 'n' Chain above a pit and platforms made of Donut Blocks. A platform with two Bony Beetles and a ? Block is found, along with a smaller Ball 'n' Chain above Donut Blocks. A Brick Block and another small Ball 'n' Chain are found. The player must cross more Donut Blocks, where they encounter Bony Beetles and a Ball 'n' Chain. A ? Block above a Bony Beetle is encountered before an area with Donut Blocks under multiple Ball n' Chains. More Bony Beetles are found in the area. Another Ball 'n' Chain appears before a ? Block and a Brick Block. Some smaller Donut Block platforms must be crossed while avoiding Ball 'n' Chains. A Bony Beetle is found, followed by a large Ball 'n' Chain above some platforms consisting of a single Donut Block. Another large Ball 'n' Chain is found next to a ? Switch, which causes red blocks to appear above the pit below. A Warp Pipe is then found. Entering the pipe leads to a path of Donut Blocks and the Goal Pole.
- Star Coin 1: The first Star Coin is located below a row of Donut Lifts and a pair of Ball 'n' Chains.
- Star Coin 2: Directly after the first Star Coin, the player should wall jump into a hidden area with a Warp Pipe. In there, the star coin is blocked off by three giant Ball 'n' Chain. A Starman, which can be found in the ? Block on the other side of the area, is required in order to safely obtain the second Star Coin.
- Star Coin 3: At the end of the stage, the player needs to hit an orange ? Switch to make red blocks appear. These red blocks will allow the player to cross the bottomless pit and reach the final Star Coin.