I’m a big FAN of religious architecture: the art of convincing people your God is important by impressing them with a building.
The one I’d most like to visit next is Tiger’s Nest Monastery in Bhutan. (Though I may need to become a monk to do so.)
Tiger’s Nest Monastery, perched precariously on the edge of a 3,000-feet-high cliff in Paro Valley, is one of the holiest places in Bhutan. Legend has it that Guru Rinpoche [wiki], the second Buddha, flew onto the cliff on the back of a tigress, and then meditated in a cave which now exists within the monastery walls.
The monastery, formally called Taktshang Goemba, was built in 1692 and reconstructed in 1998 after a fire. Now, the monastery is restricted to practicing Buddhists on religious retreats and is off-limits to ordinary tourists.

And I still haven’t seen Borobrodur in Indonesia:

Neatorama » Blog Archive » 10 Most Amazing Temples in the World
(via Dark Roasted Blend)
Neatorama also posted 10 Divinely Designed Churches (and a token Mosque).