Cheonmachong, formerly Tomb No.155 in South Korea, is a tumulus located in Gyeongju, South Korea.

Gyeongju, historically known as Seorabeol, is a coastal city in the far southeastern corner of North Gyeongsang Province, South Korea. It is the second largest city by area in the province after Andong, covering 1,324 km2 (511 sq mi) with a population of 264,091 people as of December 2012. Gyeongju is 370 km (230 mi) southeast of Seoul, and 55 km (34 mi) east of Daegu. The city borders Cheongdo and Yeongcheon to the west, Ulsan to the south and Pohang to the north, while to the east lies the coast of the Sea of Japan. Numerous low mountains—outliers of the Taebaek range—are scattered around the city.