Maybe it is not quite as jaw-dropping as Angkor Wat, but the ancient city of Ayutthaya is a must see attraction when in Bangkok. Hop on the train at Hua Lamphong Station for about $1 and take the hour or so ride out of the city to Ayutthaya. Once you arrive, grab a tuk tuk ride to middle of the ancient city and either walk around or rent a bicycle. The architecture is similar to Angkor Wat (Khmer)– with large stone temples, steep steps and tall spires. The old capital of Siam will take you back in time as you walk among the once mighty ruins. This makes for a perfect day trip from Bangkok.