From HODP Wiki

The Quad contains three undergraduate Houses, Cabot, Currier, and Pforzheimer (almost always referred to as Pfoho). The Quad is located about 10 minutes away from the Science Center Plaza, in the opposite direction of the River Houses, and used to be the dormitories for Radcliffe College. Shuttle routes between Mather and the Quad, and between the Yard and the Quad, run typically every 10-15 minutes in peak hours, and into the early-morning Horus and weekends as well.

The Quad also contains most of Harvard’s dance studio space and the SOCH (Student Organization Center at Hilles), a hub for student organizations, the location of some student activities fair, and the site of many clubs’ mailboxes or official office space.