Grand Palace Complex, Bangkok

If you're staying in the traveler's ghetto, ignore what the tuktuk drivers say: you do not need a ride, the awesome Grand Palace Complex is just a 15 minute walk. Plus you'll miss the river, the National University, the National Museum, and the huge public park Sanam Luang (which was where the happenin' activities for the King's Birthday were going on). The holiest site in Thailand, Wat Phra Kaeo (containing the non-photographable most important image of the Emerald Buddha [which apparently is photographable for certain postcard makers]) is on the complex.