Sigiriya (Lion's rock) is an ancient rock fortress and ruins of a castle situated in central Matale District of Sri Lanka. It is a popular tourist destination and also popular for the ancient paintings (frescos) very similar to the paintings in Ajanta Caves of India. It was built during the reign of King Kasyapa (477 – 495 AD) and one of the seven World Heritage Sites in Sri Lanka.

Sigiriya may have been inhabited through prehistoric times. It was used as a rock-shelter mountain monastery from about the 5th century BC, with caves prepared and donated by devotees to the Buddhist Sangha. The garden and palace were built by Kashyapa. Following Kasyapa's death, it was again a monastery complex up to about the 14th century, after which it was abandoned. The ruins were discovered in 1907 by British explorer John Still. The Sigiri inscriptions were deciphered by the archeologist Senarath Paranavithana who published a renowned two volume work, published by Oxford, known as "Sigiri Graffiti". He also wrote the popular book "Story of Sigiriya". Still further interpretations have the site as the work of a Buddhist community, with no military function at all. This site may have been important in the competition between the Mahayana and Theravada Buddhist traditions in ancient Sri Lanka

Sigiriya rock is the hardened magma plug from an extinct and long-eroded volcano. It stands high above the surrounding plain, visible for miles in all directions. The rock rests on a steep mound that rises abruptly from the flat plain surrounding it. The rock itself rises 370m and is sheer on all sides, in many places overhanging the base. It is elliptical in plan and has a flat top that slopes gradually along the long axis of the ellipse.

Sigiriya consists of an ancient castle built by King Kasyapa during the 5th century AD. The Sigiriya site has the remains of an upper palace sited on the flat top of the rock, a mid-level terrace that includes the Lion Gate and the mirror wall with its frescoes, the lower palace that clings to the slopes below the rock, and the moats, walls and gardens that extend for some hundreds of metres out from the base of the rock.

The site is both a palace and fortress. Sufficient remains to provide the visitor with a stunning insight into the ingenuity and creativity of its builders. The upper palace on the top of the rock includes cisterns cut into the rock that still retain water. The moats and walls that surround the lower palace are still exquisitely beautiful.

Sigiriya is considered as one of the most important sites of urban planning of the first millennium, the site plan is considered very elaborate and imaginative.