Possibly Myanmar's most forgotten ancient capital, Pinya rose to prominence in 1303 in the aftermath of the last wave of Mongol attacks. Its founder was upstart governor-king Thihathu, whose son, Athingaraza Sawyun, set up a rival kingdom across the river in Sagaing. The two coexisted for half a century, creating Bagan-style buildings, but today all that remains of old Pinya is a grouping of large brick stupa ruins.
Work has been done to improve their structural integrity and it's possible to enter the ruins, each of which still has buddha images visible within.
Pinya is an easy 10-minute detour en route to/from Mandalay Airport.