When I returned to Thailand second time, it give me the chance to step outside of Bangkok for the day and visit Ayutthaya, about an hour away. I took a local bus from Bangkok's northern bus terminal directly to Ayutthaya. Upon arrival, I rented a cycle and got a map from the information center and bicycled around the city to find ruins...the path is paved and distances between temples are small so it's easy to cycle around and a lot of fun!
Of all the temples, Wat Mahathat was the most interesting. It held crumbling stupas, rows of headless buddhas and this buddha-head in a tree trunk which I found fascinating.
Some of the life sized statues of the Buddha are still intact and breathtaking, especially if you are here around sunset.