The illusion is perfect. You enter the church of Santa Maria presso San Satiro (it's a complicated name) and it appears that, behind the altar, there is a large space, apse regular, well complemented by columns and decorations. But no, it is not: the illusion (deception?) lasts long, and to realize that it is just an optical illusion you have to get right next to the altar, almost touch: behind the altar no passage , there's a little less than a meter of space. In short, the apse which we see in reality does not exist. At the time of building the church, the diocese did not have the necessary permits. The reduced space made impossible the work; Bramante instead accepted the challenge and brought to scale the same measures which had originally envisaged: the fake apse measuring 97 cm instead of 9 meters and 70 cm provided in the original design; and from this impediment Bramante was able to draw a masterpiece really unexpected. In his perfect perspective construction, the work shows the influence of the research of Piero della Francesca and Donatello in the field of illusionistic representation

The Sacristy is an outstanding example of Renaissance architecture.