Tham Khao Luang is the most dramatic temple site near Phetchaburi — a large cave hollowed out of a limestone hill about 4km north of town, filled with hundreds of Buddha images of all sizes and lit by shafts of sunlight that pierce the cavern ceiling through natural openings in the rock. The light effect is strongest around midday, when the shafts illuminate the golden figures below in a way that feels almost theatrical.
The cave has been a place of worship for centuries. King Mongkut (Rama IV) had many of the larger Buddha images installed during his visits. A steep staircase leads up to the main cave entrance; there is a smaller cave entrance accessible from the other side of the hill that involves a longer walk but fewer steps.
Admission is a small donation; dress respectfully. Expect hawkers selling monkey food at the base — the macaques here are persistent. Go early or close to noon for the best light.