Cells are placed into an integrated circuit floorplan by creating clusters of cells in modules, each cluster being composed of cells in a path connected to at least one flip-flop in the module, or of cells that are not in a path connected to any flip-flop. Regions are defined in the floorplan for placement of modules, and the clusters are placed into optimal locations in modules and placing the modules into optimal locations in the regions. The coordinates for the wires, modules and clusters are selectively recalculated. The clusters are moved in the floorplan for more uniform density, and the modules are assigned to regions based on module coordinates.