GBA Bowser's Castle 1

Bowser's Castle 1 (previously known as Bowser Castle 1) is a race course in Mario Kart: Super Circuit as the fourth and last race of the Mushroom Cup. It is the first of four Bowser Castle courses raced in each cup except the Lightning Cup. The course is relatively short and contains only five Thwomps, a lot of coins, and a few item boxes. The course takes place inside the castle, as can be seen by the windows and large Bowser-symboled door in the background. It shares its music with the game's other three Bowser Castles: 2, 3, 4.

Bowser's Castle 1 returns in Mario Kart 7 as the second course of the Shell Cup and also in Mario Kart Tour, where it debuted in the New York Tour.

Course layout
After the start, there are two turns to the left. After a long straight piece there is a turn to the right with two Thwomps, with a mud-pool after it on the right. Then there is a swing curve left-right followed with three Thwomps and a bit later two turns to the left. Then there are five gaps with Lava Bubbles jumping out. After that there's a turn to the left and a swing curve right-left to the finish line.

Mario Kart 7
Bowser Castle 1 reappears in Mario Kart 7 as the second race of the Shell Cup. It is the game's only retro course from Mario Kart: Super Circuit. The track is virtually identical to the original course, but has the addition of 3D graphics like the retro courses from Super Mario Kart. To make further use of this, there are some stone pillars poking out of the lava. The number of gaps in the jump section were reduced to four, and the platforms were lengthened accordingly. Also, a Glide Ramp appears at the first jump after 36 seconds of the race have elapsed. The glider can also be used to reach a small platform within the lava to the left. There are also some added coins on the track. In addition, the flashing signs that tell which direction to go from Mario Kart: Super Circuit are now billboards attached to the track. The course now has a Mario Kart 64-style starting banner. This is also the only course in the Shell Cup not to be in the same order as its appearance in its original cup.

In version 1.1, a shortcut exploit which allowed players to skip the second 180-degree turn became unusable when playing online. The shortcut is still viable offline, however.

Mario Kart Tour
Bowser's Castle 1 reappears once more in Mario Kart Tour, first appearing in the New York Tour. It generally retains its layout from Mario Kart 7. It is a favorite of Ludwig, Bowser, Green Shy Guy, Captain Toad, King Boo (Luigi's Mansion), Dry Bones (Gold), Shy Guy (Ninja), Waluigi (Vampire), and the King Bob-omb Mii Racing Suit. This course is also a favorite of Wario (Hiker) and the Wario Mii Racing Suit if they reach level 3 and Dry Bones if he reaches level 6. Like other courses in the game, Bowser's Castle 1 has a reversed variant, a trick variant, and a reversed/trick variant, referred to as Bowser's Castle 1R, Bowser's Castle 1T, and Bowser's Castle 1R/T respectively, with the latter being introduced in the London Tour.

This course also uses the Mario Kart 7 version of its music, while most other classic courses in the game uses the original versions of their themes. It also shares its music with GBA Bowser's Castle 2, GBA Bowser's Castle 3, and RMX Bowser's Castle 1.

Prior to the 2019 Halloween Tour, no kart or glider had Bowser's Castle 1R listed as a favorite course. Instead, its appearance in the Dry Bowser Cup relied on the spotlight bonus to raise the Badwagon and Swooper up one level.

For this course's tour appearances, see List of GBA Bowser's Castle 1 tour appearances in Mario Kart Tour.

Trivia

 * The music for this course (and subsequent Bowser Castle courses) has a similar bassline to that of Bowser's battle theme in Super Mario 64.
 * The course icon for the R/T variant of this course was different in the London Tour, where the tall ramps were narrower and had Dash Panels on them. The course icon was changed after the London Tour.