Dream Shrine

The Dream Shrine is a strange building located in Link's Awakening's Mabe Village. It is unknown if Dream Shrine's main chamber is a real place or not, even by Koholint Island's standards. The doorway to the shrine is blocked by three large stones, and Link will be unable to enter until he has claimed the Power Bracelet. When he enters the shrine, it appears to be a small room with a single bed. However, if he goes to sleep, he will wake up in a large room. This room is guarded by large groups of Arm-Mimics, which act as part of a puzzle. Fifty Rupees can be found here, but the real prize of the shrine is the legendary Ocarina. Getting this item requires use of the Pegasus Boots. After leaving the room, Link will wake up in the bed found in the first room.

Trivia
In the Mysterious-Dungeon Simulation Game from The Minish Cap, Link also falls asleep in a small room with on a bed and awakens in a room filled with monsters.