A set of building blocks is presented for the hierarchical design of delay-insensitive systems. It consists of delay-insensitive (DI) building blocks and hybrid (non-DI) building blocks. An extended signal transition graph (STG) model is used for circuit specification and analysis. It permits the clear specification of delay-insensitive circuits, distinguishing between environment/module behaviour and DI/non-DI components. A hierarchical composition procedure is described for the composition of deterministic STG specifications. As an example, a circuit for distributed mutual exclusion is designed and implemented.