A connector includes a first body, a second body, a first fastener, and a second fastener. The first body has a base portion and a protrusion, the protrusion extends away from the base portion along a first direction, and the first body has a first cavity that extends into the protrusion and towards the base portion along the first direction. The second body has a second cavity, which is shaped to receive the protrusion such that rotation of the first body relative to the second body is blocked. The connector may be used to attach structural members, for example during the construction of a modular structure.