Most buildings at Queen's, including all constructed before the 1960s, are faced with limestone.
Two kinds of limestone have been used at the university: Kingston limestone, quarried locally, and Queenston limestone, quarried in the Niagara peninsula.
Kingston limestone is pale grey and was used for all major buildings before the 1930s.
With the decline of local quarries in the late 1930s, Queen's turned to Queenston limestone, which has a slightly browner shade. The first building faced with Queenston limestone was the Craine Building, which was completed in 1938.
A sure way of dating the university's stone buildings is to note the colour of the stone. Since the early 1960s many new buildings have been faced with concrete, the first of them being Watson Hall, which was completed in 1967.