|Time zone||Sri Lanka Standard Time Zone (UTC+5:30)|
The area was originally known as Welikada and stretched from the Ethul Kotte bridge to the tram terminus at Borella. The Welikada Prison was originally within the village limits.
The name Rajagiriya came from the former Governor's residence, the grounds of which extended from Madinnagoda Road in the north to the Cotta road in the south. The house and grounds were later purchased by Ananda Coomaraswamy. According to historian Douglas Ranasinghe, a Malayali servant of Coomaraswamy's saw a large mongoose in the garden and shouted 'Raja kiriya' (meaning 'large mongoose') and the name stuck.
The house was later purchased by Anagarika Dharmapala. The Hewavitharana Textile Training School was built within the grounds and later Hewavitharana Maha Vidyalaya. The house and the truncated lands were later acquired by the Obeyesekere family and it is generally known as the 'Obeyesekere Walauwa'.
The area around the Ethul Kotte bridge became a light industrial area, with the 'Electroplastics' and 'Pinnacle' factories and the Ceylon Transport Board's ticket machine workshops.
Several historic buildings in the area have been destroyed. These include the ancient Ambalama (rest house) and the 'Welikada Hotel and Bakery' at the Welikada junction, The 'Shermila' cinema (originally the Kotte urban development council's first market) and several old houses.
Many of the area's marshes, which were the habitat of birds within the Sri Jayawardenapura Kotte Bird Sanctuary, and which were designated as flood-retention areas, were filled up and built on in spite of the protests of the residents.
In the late 1970s the government of JR Jayawardene ran a major road through the very middle of the EW Perera Park (which commemorated a national hero and was the venue for Football, Cricket and other sports).
Areas in Rajagiriya
The Sri Jayawardenapura Kotte municipal ward of Rajagiriya is confined to the areas around the original grounds of the Governor's house.
The Rajagiriya postal area (also known as the Welikada postal area) also includes Kotiyagoda and Kalapaluwawa within the Kaduwela Pradeshiya Sabha council limits.
Rajagiriya within the Kotte municipal limits comprises:
- Ward no. 1 - Rajagiriya (includes Rajagiriya proper - the area around the Governor's house - Obeyesekerepura, Moragasmulla and Madinnagoda road, bounded by the Kolonnawa Ela canal on the north, the Heen Ela canal on the west, the Cotta Road on the south and the Welikada ward on the east);
- Ward no. 2 - Welikada (includes Welikada proper, and stretches from the Welikada junction to the Ethul Kotte junction, bounded by the Kolonnawa Ela canal on the north and east, Ward 1 on the west, and the Cotta Road on the south).
- Ward no. 3 - Welikada-Nawala (includes Bandaranaikepura and Royal Gardens, the Municipal offices and the western half of Nawala and of Koswatte, bounded by the Cotta Road on the north, the Heen Ela canal on the west, the Diyawanna Oya canal on the south and the Nawala Road on the east).
- Ward no. 4 - Nawala (includes Welikadawatte, eastern Koswatte and Nawala, bounded by the Cotta Road on the north, the Nawala Road on the west and the Diyawanna Oya canal on the south and east).
- 'Rajagiriya', the old governor's mansion (the 'Obeyesekere Walauwa') at Rajagiriya
- The Sri Jayawardanapura Kotte Municipal Council building on Nawala Road
- the Anglican Church of St Stephen (the gal-palliya or stone church) at Moragasmulla
- the Muslim mosque on the Nawala Road
- the EW Perera Children's Park (what remains of the old park and football ground) on the Nawala Road
- the Roman Catholic Sacred Heart Church at Rajagiriya proper
- The Hewavitharana Textile training school on Dharmapala Mawatha, Rajagiriya
- Presidens College, Rajagiriya
- Many institutions such as the Elections Department, Official Languages Department and the Kachcheri are based in Ward no. 3.
- STF Camp
- Douglas Ranasinghe, Welikada viththi, 1991
- Dilrukshi Handunnetti, 'School of Rebellion', Sunday Times, 14 September 1997