Bahn Vichien, as it's called in Thai, was built in the time of King Narai to house foreign ambassadors (mainly, the French ambassador) who were the visiting Siam in the late seventeenth century. Construction of the lavish residence was overseen by Constantine Phaulkon, a Greek-born close adviser to Narai, who wanted to impress the French. When the French embassy departed, Phaulkon used the residence as his own.
The entrance to the compound faces right down Rue De France road, at the other end of which is a gate directly into the middle court of the palace. On the far left as you enter the grounds is the main house, which appears to have had decorative oval pools on either side. On the right is a large reception hall, while in between and further back is a small Catholic chapel.
The buildings are all in a very European style, and constructed in brick, which was very rare for residences of the time. As ruins go, these are perhaps the most unique buildings in all of Thailand.
Bahn Vichayen is open daily and carries an admission fee of 50 Baht (1.30 USD).