Close to the Crocodile Farm in Samut Prakan Province, the 320-hectare "city" features 116 structures of Thailand's famous monuments and architectural attractions.

Outstanding works include the former Grand Palace of Ayutthaya (destroyed in the Burmese invasion of 1767), Phimai Sanctuary in Nakhon Ratchasima, and Wat Khao Phra Viharn on the Cambodian border.

Initially, he intended to build a Thai map-shaped golf course where miniatures of important national ancient sites were placed, which aimed to serve tourism and education purposes only.

Thus, he changed the concept of the Ancient City from being a tourism attraction and relaxation to an open-air museum for education purpose to benefit newer generations who would be proud of their national heritage.

Lek continually created artwork in the Ancient City as well as the Sanctuary of Truth in Pattaya and the Erawan Museum in Samut Prakan until the end of his life on 17 November 2000.