The highest confirmed Jenga tower built under official rules was 40 complete levels and 2 blocks and was built by Robert Grebler in 1985. This corresponds to 24.19 inches in height.
Jenga officially starts with a square, 18-level tower that consists of three blocks per level. Each layer of blocks is stacked perpendicularly to the last. Players build the tower by removing one brick at a time and adding it to the top of the tower in the same manner as the tower is initially constructed. Players can bump the tower to find loose bricks as long as they do not disturb the structure, and they can only use one hand at a time to remove a brick. When the tower falls, even if that only means one brick unintentionally fell from the tower, the game ends.