Brunelleschi's design was based on Classical Roman, Italian Romanesque and late Gothic architecture. The loggia was a well known building type, such as the Loggia dei Lanzi. But the use of round columns with classically correct capitals, in this case of the Composite Order, in conjunction with a dosserets (or impost blocks) was novel. So too, the circular arches and the segmented spherical domes behind them. The architectural elements were also all articulated in grey stone and set off against the white of the walls. This motif came to be known as pietra serena (Italian: dark stone). Also novel was the proportional logic. The heights of the columns, for example, was not arbitrary. If a horizontal line is drawn along the tops of the columns, a square is created out of the height of the column and the distance from one column to the next. This desire for regularity and geometric order was to become an important element in Renaissance architecture.