The first light was powered by kerosene oil and could be seen seventeen miles out to sea in clear weather. According to the plaque on the side of the lighthouse it displayed its beam seaward every five seconds. On the top of the semi-globe roof is a metal arrow on a pole. It points in the direction the wind is blowing. The idea of building a lighthouse for Colombo Harbour to help shipping navigate into the harbour and miss the lethal rocks, was proposed in 1815. The lighthouse was built in 1856.
The presidential house and gardens are nearby but they are unfortunately off limits to the public. It is also the home of the Sri Lankan Navy so security is very high.
When measuring distances from one city to another, instead of working out what is the centre of Colombo the Lighthouse Clock Tower is used as the starting point. The Chatham Street lighthouse plans always made an allowance for the positioning of a clock on the outside. This feature was added later. The clock was ordered in 1872 but not installed. It was kept in storage in a warehouse for economic reasons. It was finally put in the tower in 1914. The clock was visible for some distance and would help local workers to be punctual as many could not afford a watch.