The Frank Lloyd Wright house that floats over a Bloomfield Hills ravine

Part of the house hangs out over the ravine on slim posts, so that from the wooded downslope it looks less built than perched. Gregor and Elizabeth Affleck moved into it in 1941, and Frank Lloyd Wright designed every line of it — though not as one of his famous show-pieces. This was Wright chasing a smaller idea that consumed him for years: a well-made house an ordinary family could actually afford. He called the type Usonian, and Oakland County has one of the few you can walk inside.

The Usonian rulebook is all over the place. No attic, no real basement. One flowing room where kitchen, dining, and living blur together instead of three boxes with doors. A flat carport instead of a garage — Wright coined that word here, in houses like this. Brick, wood, and glass, with long bands of windows pulling the surrounding trees into the rooms. A reflecting pool sits at the heart of the plan, open to the ravine. If the layout feels oddly familiar, that is the point: the open floor plan most American homes now take for granted traces straight back to designs like this one.

Wright finished only about two dozen Usonians before World War II froze the building trade, which is what makes a tourable one unusual. The Affleck children handed the house to Lawrence Technological University in 1978, and the school’s architecture students have looked after it ever since — sweeping the cantilevered terrace, studying the joinery, learning the master’s tricks by living with them.

The university runs guided tours by season rather than letting people drift in off Woodward, so a visit takes a little planning. Worth it for the moment you step onto that terrace and realize the floor under your feet is holding nothing up but air and a long view of the trees.