The Colombo–Katunayake Expressway  E03  is Sri Lanka's second E Class highway. The 25.8-kilometre-long (16.0 mi) highway links the Sri Lankan capital Colombo with Bandaranaike International Airport, Katunayake and Negombo. Construction on the highway began in October 2009, and it was opened on 27 October 2013, by former president Mahinda Rajapaksa. The highway has three lanes each way from Colombo to Peliyagoda, and two lanes each way from Peliyagoda to Katunayake, with the width ranging from 26 to 33.5 metres.

Colombo is the executive and judicial capital and largest city of Sri Lanka by population. According to the Brookings Institution, the Colombo metropolitan area has a population of 5.6 million, and 752,993 in the Municipality. It is the financial centre of the island and a tourist destination. It is located on the west coast of the island and adjacent to the Greater Colombo area which includes Sri Jayawardenepura Kotte, the legislative capital of Sri Lanka, and Dehiwala-Mount Lavinia. Colombo is often referred to as the capital since Sri Jayawardenepura Kotte is itself within the urban/suburban area of Colombo. It is also the administrative capital of the Western Province and the district capital of Colombo District. Colombo is a busy and vibrant city with a mixture of modern life, colonial buildings and monuments.