 When Antonio da Sangallo was commissioned to rebuild the church , his main problem was its shape ; its width , facing Piazza Scossacavalli , was longer than its depth ( along Borgo Vecchio ) . Drawings in the Uffizi indicate several solutions : a single @-@ nave plan , oriented along its long side with a side entrance , and octagonal and oval plans . The latter was adopted by Giacomo Barozzi da Vignola for the church of Sant 'Anna dei Palafrenieri , and became popular during the 17th century . Sangallo did not adopt any of these plans , instead deciding to reduce the area of the church , whose plan became a rectangle with its long side normal to Piazza Scossacavalli . Its nave was flanked by four large niches , and Sangallo designed four rooms ( two on each side ) as sacristies . 
