Khao Chi Chan, often called Buddha Mountain, is a monumental Buddha outline cut into a limestone cliff south of Pattaya. This is an open-air landmark and devotional image, not a temple interior.
Thailand's official tourism directory says the image was created for the 50th anniversary of King Bhumibol Adulyadej's accession to the throne in 1996. The seated Buddha is shown in the posture of subduing Mara, with artistic influence from Sukhothai and Lanna traditions.
The government listing gives the cliff image a height of 109 metres. Its effect comes from seeing the gold-filled outline against the exposed rock, so the wider view matters more than getting close to the cliff. Stay within marked public areas and check current local notices before travelling.