The Reclining Buddha of Wat Pho
If you only see one temple in Bangkok, make it Wat Pho: home of the largest reclining Buddha in Thailand. The 141-foot-long statue is an artistic masterpiece plated in gold leaf and inlaid with mother of pearl. You could easily spend all day wandering the grounds, looking at reliquaries, visiting the massage school, and admiring the 400 statues of Buddha in the outer cloister—each posed and sculpted slightly differently. Before you leave, drop some money in one of the 108 begging bowls (one bowl for each of the characters of Buddha). The money goes to maintaining the Wat and the gift will bring you good luck. That seems like a fair trade.