To be a building, half of a structure's height must have usable floor space.

VOA: special.2010.03.31

He arranged them carefully, put coins underneath some fruit to vary their height, and painted their structure and patterns.

NPR: Touring Cezanne's Cultural Roots

Twenty feet wide, it is the building's organizing element and circulation spine, connecting the first four floors and continuing upward with bridges across the space and a narrower stair above as it ascends to the structure's full nine-story height.

WSJ: Cooper Union's New Building, at 41 Cooper Square | By WSJ Architecture Critic Ada Louis Huxtable

The structure, which has a span of 6.4m (21ft) and a height of 1.3m (4ft 3in), is being built on the site of a disused horse bridge.

BBC: Work begins on 'giant Meccano bridge' in Bolton