Ta Keo is one of the earliest of Angkor's sandstone temple-mountains, built by Jayavarman V in the late 10th century, and it has a striking severity that sets it apart from the intricate decoration of later temples. The five towers rise steeply from a series of platforms, and the staircases are among the most nearly vertical at Angkor — the climb to the summit requires holding the railings and considerable care. But the effort is worth it: the view from the top takes in the treetops of the surrounding forest and a sense of the scale of the central Angkor complex.
The absence of carving, while the result of a historical accident (or a bad omen, depending on which account you follow), means that Ta Keo's structural qualities are more apparent than at any other temple. The proportions are excellent and the grey-green sandstone has an almost modernist quality. It sits between Ta Prohm and the Angkor Thom east gate and makes a logical stop on the "large circuit" that most tuk-tuk drivers follow.