Trifora

The trifora usually appears in towers and belfries—on the top floors, where it is necessary to lighten the structure with wider openings.

[1][2][3] The trifora has three openings divided by two small columns or pilasters, on which rest three arches, round or acute.

Less popular than the mullioned window, the trifora was, however, widely used in the Romanesque, Gothic, and Renaissance periods.

Later, the window was mostly forgotten, coming back in vogue in the nineteenth century, in the period of eclecticism and the rediscovery of ancient styles (Neo-Gothic, Neo-Renaissance, and so on).

Compared to the mullioned window, the trifora was generally used for larger and more ornate openings.