When Enea Piccolomini occupied the papal throne as Pius II, his idea of creating a people-friendly city became possible. Enea Piccolomini knew the architecture of the German Hallenkirche, hall churches, and he wanted the three naves in the Pienza Cathedral to be the same height. The architecture was also to keep the Gothic lines of the Franciscan churches, create wealth with sobriety, and Leon Battista Alberti had shown that he was able to implement his ideas, having built Santa Maria Novella in Florence. The facade designed by Alberti's pupil, Rossellino, is divided into three areas corresponding to the naves inside it. A string course divides the facade into two parts: in the lower part there are three entrance doors and in the upper part three arches supported by columns. The coat of arms of the Holy See and of the Piccolomini family dominates the tympanum of the facade.
The interior of the church has a Latin cross layout divided into three naves, equal in height, with the central nave wider than the lateral naves. Gothic windows on the walls provide great lighting, creating an evocative and intense atmosphere. The interior of the church is enriched with paintings by the most famous artists of the time. The architecture of the bell tower is very simple and narrow; it was damaged by the earthquake in 1545 and was restored in 1570. The Cathedral was consecrated by Pius II on August 29, 1462.