Piazza del Papa (actually Piazza del Plebiscito) takes his name from the statue of Pope Clemente XII Corsini which stands in his centre. It is, starting from 1446, the most significant and amazing urban space in the city of Ancona, surrounded by several civil and public building, fountains and monumental churches. This study analyzes all of them, one by one, wirh historical engravings, photos and architectural surveys, as well with thorough historical notes.