The Main Building of RMC was built in sections as needs for more size increased over the years. The original building was erected in 1963, and the double gym was added in 1988. Not much is known for the other additions, they were either part of the original construction of the building, or added on in 1967, when it became a boys boarding school. Compared to many other secondary schools in the London area, RMC has a very simple, linear layout.