Give a kid some crayons and ask him to draw a house, and the result will probably look a lot like a Denver Square. You see them all over the city, those cubic, two-story brick houses from the late 19th and early 20th centuries. Sturdy, statelly, and, yes, boxy, the Denver Square - genericallly known as a Foursquare, and not unique to the Mile-High City - is a paragon of architectural efficiency, offering a large amount of interior space on smallish lots. Although they are simpler and less detailed than the ornate Queen Annes that preceded them, their relative plainness has always been part of their appeal.