The distinctive cupola on the roof of St. Matthew's is the active working part of a 100 per cent wind-driven ventilation system, in operation since 1924. The rotating fan you can see from the street is six feet (1.8 metres) in diameter and pulls air through the building as it turns.
Cupolas such as this are more common in the architecture of New England. The cupola is a local landmark, used by the local BIA on its neighbourhood banners. It is currently in need of repair because of a broken strut.