Mies van der Rohe's Farnsworth House carries the principle of 'less is more' to the most extreme simplicity it can reach in a house. The idea of fluid, columnless space tried at the Barcelona Pavilion is here reduced to a single pure gesture: a glass box suspended in the air in the middle of nature.

The house stands on the bank of a river in a floodplain, raised about 1.5 metres off the ground. The whole structure hangs from eight white-painted steel H-columns; the roof and floor slabs are welded to the outside of these columns, so the columns never enter the space. The interior is a single, continuous, columnless area; apart from a wooden core housing the bathroom and services, there is no dividing wall. All four faces are glass top to bottom — there is no wall, only glass and the landscape beyond it.

Farnsworth tests an ideal by removing architecture almost entirely: can shelter be the thinnest, most invisible boundary between the human and the environment? The result is technically difficult (the glass box overheats in summer and chills in winter; the house has flooded) but conceptually pure — structure reduced to eight columns, envelope to a single pane of glass, space to one volume. Mies's experiment is the philosophical core of the glass-tower and transparent-architecture aesthetic of the next half-century: the less building there is, the purer the architectural idea appears.