As circuit sizes have increased, designs have become increasingly hierarchical. It is common for designs to have large numbers of macro blocks; many of these blocks are “soft,” and may have variable width and height. The present invention provides an alternate method to handle designs with large numbers of blocks. Rather than approaching them as expanded floorplanning, the problems are re-cast as traditional mixed size placement, and many macro blocks are treated as standard cells. Using existing mixed size placement tools, the superior reported are obtained. First, an effective “standard block design” methodology is provided. Second, new mixed size placement legalization algorithms that are more robust than the widely-used mixed-size Tetris algorithm is presented.