Due to its large harbour and its strategic position along the East-West sea trade routes, Colombo was known to ancient traders 2,000 years ago. It was made the capital of the island when Sri Lanka was ceded to the British Empire in 1815, and its status as capital was retained when the nation became independent in 1948. In 1978, when administrative functions were moved to Sri Jayawardenepura Kotte, Colombo was designated as the commercial capital of Sri Lanka.
Like many cities, Colombo's urban area extends well beyond the boundaries of a single local authority, encompassing other municipal and urban councils such as Sri Jayawardenepura Kotte Municipal Council, Dehiwala Mount Lavinia Municipal Council, Kolonnawa Urban Council, Kaduwela Municipal Council and Kotikawatte Mulleriyawa Pradeshiya Sabha. The main city is home to a majority of Sri Lanka's corporate offices, restaurants and entertainment venues. Famous landmarks in Colombo include Galle Face Green, Viharamahadevi Park, Beira Lake, Colombo Racecourse, Planetarium, University of Colombo, Mount Lavinia beach, Nelum Pokuna Theatre, Colombo Lotus Tower as well as the National Museum.
Another belief is that the name is derived from the Sinhalese name කොල-අඹ-තොට Kola-amba-thota which means "Harbour with leafy mango trees". This coincides with Robert Knox's history of the island while he was a prisoner in Kandy. He writes that, "On the West the City of Columbo, so called from a Tree the Natives call Ambo, (which bears the Mango-fruit) growing in that place; but this never bare fruit, but onely leaves, which in their Language is Cola and thence they called the Tree Colambo: which the Christians in honour of Columbus turned to Columbo."
The author of the oldest Sinhalese grammar, Sidatsangarava, written in the 13th century wrote about a category of words that exclusively belonged to early Sinhalese. It lists naramba (to see) and kolamba (ford or harbour) as belonging to an indigenous source. Kolamba may also be the source of the name of the commercial capital Colombo.