The bridge is a thing of this sort. The location allows the simple onefold of earth and sky, of divinities and mortals, to enter into a site by arranging the site into spaces. The location makes room for the fourfold in a double sense. The location admits the fourfold and it installs the fourfold. The two—making room in the sense of admitting and in the sense of installing—belong together. As a double space-making, the location is a shelter for the fourfold or, by the same token, a house. Things like such locations shelter or house men's lives. Things of this sort are housings, though not necessarily dwelling-houses in the narrower sense.

The making of such things is building. Its nature consists in this, that it corresponds to the character of these things. They are locations that allow spaces. This is why building, by virtue of constructing locations, is a founding and joining of spaces. Because building produces locations, the joining of the spaces of these locations necessarily brings with it space, as spatium and as extension into the thingly structure of buildings. But building never shapes pure "space" as a single entity. Neither directly nor indirectly. Nevertheless, because it produces things as locations, building is closer to the nature of spaces and to the origin of the nature of "space" than any geometry and mathematics. Building puts up locations that mane space and a site for the fourfold. From the simple oneness in which earth and sky, divinities and mortals belong together, building receives the directive for its erecting of locations. Building takes over from the fourfold the standard for all the traversing and measuring of the spaces that in each case are provided for by the locations that have been founded. The edifices guard the fourfold. They are things that in their own way preserve the fourfold. To preserve the fourfold, to save the earth, to receive the sky, to await the divinities, to escort mortals—this fourfold preserving is the simple nature, the presencing, of dwelling.

Martin Heidegger (GA 7) Poetry, Language, Thought

GA 7 p. 160-161