Powder House Square is a neighborhood and landmark rotary in Somerville, Massachusetts, United States. It is also known locally as Powder House Circle. It is the six-way intersection of College Avenue, Broadway, Warner Street, and Powder House Boulevard. Powder House Square stands at the southern tip of Tufts University's main Somerville/Medford campus, and borders the northern edge of Nathan Tufts Park. The square takes its name from the 18th century Powder House, which overlooks the rotary from Nathan Tufts Park.