Rock House Army Camp is a military base located at Modera, north of Colombo in the Western Province of Sri Lanka.

The base gains its name from the Rock House, a stately home built in the nineteenth century by Henry Augustus Marshall, an Englishman who accompanied Lord North who was the first British Governor of Ceylon.

Later it became the residence of Sir William Coke, the Chief Justice of Ceylon.

The estate was taken over by the British Army and the Modera battery of three BL 6 inch Mk VII naval guns within casemates and with individual underground ammunition stores, with a Fire control tower and concrete quarters that were built for the gun crews.

With the outbreak of World War II, the coastal batteries in Colombo were manned by the 1st Coast Regiment, Ceylon Garrison Artillery.