According to the ancient Sri Lankan chronicle the Culavamsa, this site was selected by King Kashyapa (477 – 495 AD) for his new capital. He built his palace on the top of this rock and decorated its sides with colourful frescoes. On a small plateau about halfway up the side of this rock he built a gateway in the form of an enormous lion. The name of this place is derived from this structure — Sīnhāgiri, the Lion Rock (an etymology similar to Sinhapura, the Sanskrit name of Singapore, the Lion City).

John Still in 1907 wrote, "The whole face of the hill appears to have been a gigantic picture gallery. the largest picture in the world perhaps". The paintings would have covered most of the western face of the rock, an area 140 metres long and 40 metres high. There are references in the graffiti to 500 ladies in these paintings. However, most have been lost forever. More frescoes, different from those on the rock face, can be seen elsewhere, for example on the ceiling of the location called the "Cobra Hood Cave".

Sigiriya is considered to be one of the most important urban planning sites of the first millennium, and the site plan is considered very elaborate and imaginative. The plan combined concepts of symmetry and asymmetry to intentionally interlock the man-made geometrical and natural forms of the surroundings. On the west side of the rock lies a park for the royals, laid out on a symmetrical plan; the park contains water-retaining structures, including sophisticated surface/subsurface hydraulic systems, some of which are working today. The south contains a man-made reservoir; these were extensively used from the previous capital of the dry zone of Sri Lanka. Five gates were placed at entrances. The more elaborate western gate is thought to have been reserved for the royals.

Sigiriya consists of an ancient citadel built by King Kashyapa during the 5th century. The Sigiriya site contains the ruins of an upper palace located 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 palaces clings to the slopes below the rocks. The moats, walls and gardens of the palace extended for a few hundred metres from the base of the rock. The site was both a palace and a fortress. The upper palace on the top of the rock includes cisterns cut into the rock.

Sigiriya consists of an ancient citadel built by King Kashyapa during the 5th century. The Sigiriya site contains the ruins of an upper palace located 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 palaces clings to the slopes below the rocks. The moats, walls and gardens of the palace extended for a few hundred metres from the base of the rock. The site was both a palace and a fortress. The upper palace on the top of the rock includes cisterns cut into the rock.

In 477 AD, Kashyapa I, the king’s son by a non-royal consort, seized the throne from King Dhatusena, following a coup assisted by Migara, the King’s nephew and army commander. The rightful heir, Moggallana, fearing for his life, fled to South India. Afraid of an attack by Moggallana, Kashyapa moved the capital and his residence from the traditional capital of Anuradhapura to the more secure Sigiriya. During King Kashyapa’s reign (477 to 495 AD), Sigiriya was developed into a complex city and fortress. Most of the elaborate constructions on the rock summit and around it, including defensive structures, palaces, and gardens, date from this period.

The Culavamsa describes King Kashyapa as the son of King Dhatusena. Kashyapa murdered his father by walling him up alive and then usurping the throne which rightfully belonged to his half-brother Moggallana, Dhatusena's son by the true queen. Moggallana fled to India to escape being assassinated by Kashyapa, but vowed revenge. In India he raised an army with the intention of returning and retaking the throne of Sri Lanka, which he considered to be rightfully his. Expecting the inevitable return of Moggallana, Kashyapa is said to have built his palace on the summit of Sigiriya as a fortress as well as a pleasure palace. Moggallana finally arrived, declared war, and defeated Kashyapa in 495 CE. During the battle Kashyapa's armies abandoned him and he committed suicide by falling on his sword.