Ban Wichayen, also known as the Residence for Foreign Envoys, was built to house French ambassadors and later became the home of Constantine Phaulkon. The architecture within the compound is a hybrid style, where traditional Thai buildings stand alongside elegant European-style structures. A key highlight is the Christian chapel, which has a Thai-style exterior but features European arched doorways and windows, the first of its kind. The main construction used thick brick and plaster following French engineering, while still being decorated with high-quality stucco craftsmanship. Today, this historical site is located near Phra Prang Sam Yod, serving as a landmark that tells stories of prosperity and court politics in Lopburi.