This paper establishes a framework that hierarchically integrates symbolic and sub-symbolic representations in an architecture for cognitive robotics. It is formalised abstractly as nodes in a hierarchy, with each node a sub-task that maintains its own belief-state and generates behaviour. An instantiation is developed for a real robot building towers of blocks, subject to human interference; this hierarchy uses a node with a concurrent multitasking teleo-reactive program, a node embedding a physics simulator to provide spatial knowledge, and nodes for sensor processing and robot control.