閣

To keep this distinct from other kanji such as "watchtower" and "pagoda", I use the mnemonic "towering tower". -- In some old 8-bit kung-fu videogame, with a plot similar as Bruce Lee's last, unfinished movie, the hero must break through a gate at each level of the towering tower, fighting with opponents using various styles of kung-fu until he meets the finale at the topmost level of the "towering tower".

Source: Kanji Koohii community