611 AD, near Jinan City
The Four-Entrance Pagoda lies about 36km from Jinan on the road to Mt. Tai. Dated 611 (Sui dynasty) by an inscription on one of the roof beams, this is the oldest stone pagoda in China1. It is built of ashlar stone blocks, with corbeled eaves. The square plan is about 7m on a side, with a total height of 15m. Built in Kushan style, the stupa is topped with a Sumeru-style harmika; the building as a whole also represents the world mountain.
Inside, there is a central pillar with four buddhas overlooking the cardinal directions. At least one of these images is 60 years older (ca. 544) than the building itself, according to a now-lost dedicatory inscription.
1Statements like this always have to be read carefully. Burial pagodas do not count, and there is an older brick pagoda (the Song Yue Si Ta, near Dengfeng) in Henan dated 523.