Architecture descriptions are important for reasoning about system properties in order to make the right architectural decisions for building systems with adequate quality. Modularising concerns at the architecture description level may ease system configurability and cater for variations in architectural requirements. We devise a technique for modularising and composing complex architectural connectors described in UML using structured classes. We define a binding language with lexical and graphical syntax to support the composition. Finally, we discuss the relationship with standard UML constructs.