The exterior of the building is of Byzantine architecture, with its elaborately carved heads of the four massive outer pillars. The letters A.M.D.G. (Ad Majorem Dei Gloriam – which when translated means ‘For the greater glory of God’) and year of the dedication are carved on the wall over the West door. The Byzantine style was chosen as it best served the needs of the College; and although it had no connection with any local style, it was of eastern origin and did not seem to be inappropriate for its use in Sri Lanka.
The interior of the Chapel consists of a high and wide nave between the western entrance and gallery and the high alter in the eastern apse. The great roof beams, carved in a simple motif, are supported on pillars, and one of the few decorative features of the Chapel is the variety of the designs moulded on the capitals of the lower pillars. They are all different from each other, with one exception; and a keen eye is needed to spot the identical pair. In later years, when Warden De Saram had the Chapel white washed, he had the various designs effectively displayed by picking out the patterns in white against the blue background.