The Tharaba Gate is the only secular structure surviving from Bagan’s glory days and the only remaining entrance to the grounds of the old palace. Just within the gate and to the north is the modern reconstruction of the Bagan Golden Palace, which isn’t worth the $5 government entry fee. More interesting is Mahabodhi Paya to the west of it, notable for being Indian in style. Bupaya, on the riverside, is a reconstruction but has good views and is popular with local visitors.
The main cluster of buildings is to the south of the main road, including Thatbyinnyu Pahto, the highest temple in Bagan, although you can’t climb up. You can, however, at Mahazedi, a bell-shaped stupa opposite that has good views. Other highlights include single-storey Pahtothamya, dimly lit like other Pyu-style temples (later Bamar buildings are typically lighter, with higher ceilings). This does mean that what natural light enters seems particularly dramatic. Look out also for Pitakat Taik, believed to have been built by Anawrahta to house the Buddhist texts that he brought back after conquering the Mon kingdom, and Nathlaung Kyaung, where he hid away nat animist images as he subsequently imposed Theravada Buddhism.
On the western side of the main road, after it has curved southwards, is imposing two-storey Gawdawpalin Pahto. At 55m it’s one of the tallest in Bagan, but you can’t access the upper storey.