Rajagala (The Monarch's Rock), commonly Rassaagala or Rajagalathenna, is a rugged and heavily forested mountain situated 1,038 feet (316 m) above sea level, in a sparsely populated part of Eastern Province, Sri Lanka which has an important archaeological value.

The Rajagala archaeological site is only second to the Mihintale monastery in Anuradhapura and it spreads over 1,600 acres (650 ha; 2.5 sq mi).

[6] It is believed that ashes of the Arahath Mahinda Thero and his disciple "Itthiya Thera"(latter name being given as Idika)[5] were enshrined in a stupa here.

During his father's governorship of Digamadulla, his son Prince Lanja Tissa and his family embellished Rajagala on a lavish scale.

[4] Prince Lanja Tissa continued his patronage even after he ascended the throne of Anuradhapura, transforming this remote hermitage into one of the greatest monasteries in the Kingdom of Ruhuna and the name Rassagala became Rajagala (The King's Rock).

A roadway leads down across the rock, passing Chaityas, viharas, dwellings and dining halls.

[1] According to archaeological sources, the temple belongs to the most prosperous era in Sri Lankan history.

Many dagobas, temples, ponds, shrine rooms and sandakadapahana(moonstone) have been discovered from the site.

Further in the jungle there is a large block of stone about 16 feet (5 m) long with a half-carved Buddha image.