An integrated circuit design is routed by first creating temporary routes in a flattened layout, generating blockage information for sub-blocks in the layout based on the temporary routes, and establishing a routing order for cells using a depth-first search. Cells in the original layout are then routed according to the routing order using the blockage information. The temporary routes are sorted into internal routes, terminal routes, and spanning routes. Blockage information for each sub-block includes a first cellview equal to the internal routes, a second cellview equal to the terminal routes plus the spanning routes, and a third cellview equal to the total tracks in the sub-block minus the first and second cellviews. The invention is particularly suited for routing a hierarchical integrated circuit design. By examining the complete hierarchy, the invention ensures that enough metal will be remaining at upper level sub-blocks to complete the routing automatically.