Rapunzel's Tower is hidden in a large rock pit by a cave. The cave leads out into the forest with its opening hidden by a curtain of plants. At the base of the tower is an alternate entrance Mother Gothel used to go in and out of the tower before she took Rapunzel and in the years that she was too young to pull her up, with a hidden trapdoor leading up into the main rooms of the Tower.
Within the tower and over the years, Rapunzel has painted a series of murals. The tower has several rooms including bedrooms for both Rapunzel and Mother Gothel, a central room which would be the primary location of Rapunzel's gallery, and a staircase leading to an upstairs room.
In Walt Disney World, the tower was at Epcot, as part of "The Flower & Garden Festival" in 2011. It is currently at Magic Kingdom for the Fantasyland expansion, it opened 2013 and contains with its themed restroom.
There are several astronomical based paintings inside Rapunzel's chamber, including an accurate star map and a diagram of the Solar System, with one of Corona's sun emblems representing the Sun (although incorrectly depicted with eight planets (Mercury to Neptune) and five dwarf planets (Ceres, Pluto, Haumea, Makemake, and Eris), which is the current lineup, instead of stopping at Uranus, the outermost planet at the time of the film's events). This was most likely intentional since Rapunzel likely tracked the position of the stars and planets in the sky to determine the next lantern lighting festival.
Unlike the original fairy tale, where the tower had only one room with no stairs, the Tower in the film has three separate rooms (Rapunzel's room, Mother Gothel's room, and the Living room) along with stairs.
Originally, the Tower was supposed to be in the center of a ruined kingdom destroyed by a catastrophic landslide, but the animators decided to scrap the idea. However, this concept was eventually used in Into the Woods, where Rapunzel's Tower is among unspecified ruins.
Considering the fact that Rapunzel's hair is 70 feet (21 meters) long, that means when Rapunzel is seen throwing her hair down to leave the tower, and she safely manages to reach the end of her hair without running out of hair, it means that her tower is at least 35-40 feet (10-12 meters) tall (the average height of towers).
When Rapunzel was first introduced, the inside of the tower is bright and full of color. After she returns from seeing the lanterns, the tower is dull and darkly colored, which symbolizes she no longer sees it as "amazing".