Atmospheric ruins and lively temple worship can both be experienced at Wat Phutthai Sawan. King U Thong founded this temple in 1353 on the south bank of the Chao Phraya River at the spot where he and his followers lived before moving onto the island to create their great city. It's one of the few places spared by Burmese invaders and its bone-white, late-Ayuthaya-period prang (Khmer-style spire) still rises high above the old half of this temple complex. It's beautifully illuminated at night.
You can climb up inside the prang to see the massive relic vault, a reclining Buddha and lots of bats – because of the later, you do not need to remove your shoes.
Gold Buddhas on mosaicked pedestals surround the prang and east of this cloister is a stately stone Buddha reclining in a ruined building.
West of the cloister, the upper floor of the stark white and brown abbot's residence (between the modern prang and the king statues) has faded 17th-century murals.