doorways of temples
The styles of portals are Doric, Ionic, and Attic. In the Doric, the symmetrical proportions are distinguished by the following rules. Let the top of the corona, which is laid above the casing, be on a level with the tops of the capitals of the columns in the pronaos. The aperture of the doorway should be determined by dividing the height of the temple, from floor to coffered ceiling, into three and one half parts and letting two and one half thereof constitute the height of the aperture of the folding doors. Let this in turn be divided into twelve parts, and let five and a half of these form the width of the bottom of the aperture. At the top, this width should be diminished, if the aperture is sixteen feet in height, by one third the width of the door-jamb; if the aperture is from sixteen to twenty-five feet, let the upper part of it be diminished by one quarter of the jamb; if from twenty-five to thirty feet, let the top be diminished by one eighth of the jamb. Other and higher apertures should, as it seems, have their sides perpendicular. Further, the jambs themselves should be diminished at the top by one fourteenth of their width. The height of the lintel should be equivalent to the width of the jambs at the top. Its cymatium ought to be one sixth of the jamb, with a projection equivalent to its height. The style of carving of the cymatium with its astragal should be the Lesbian. Above the cymatium of the lintel, place the frieze of the doorway, of the same height as the lintel, and having a Doric cymatium and Lesbian astragal carved upon it. Let the corona and its cymatium at the top of all be carved without ornamentation, and have a projection equal to its height. To the right and left of the lintel, which rests upon the jambs, there are to be projections fashioned like projecting bases and jointed to a nicety with the cymatium itself. (Vitruvius, 15BCE)