Sambor Prei Kuk can only be reached by an excursion leaving Kampong Thom. It is Cambodia's most important pre-Angkorian architectural site. The city, built by King Isanavarman I in the 7C, was once the capital of the kingdom of Tchen-la and bore the name Isanapura (town of Isana). The ruins of about 50 brick towers and shrines are still dotted around the undergrowth and form a very serene place; some are decorated with extraordinary bas-reliefs of "flying palaces".