Pavia Cathedral is a church in Pavia, Italy, the largest in the city and seat of the Diocese of Pavia. The construction was begun in the 15th century on the site of two pre-existing Romanesque, "twin" cathedrals. The cathedral houses the remains of St. Sirus, first Bishop of Pavia, and a thorn purported to be from the Crown of Thorns worn by Christ. The marble facing of the exterior was never completed.

The Diocese of Pavia is a Latin diocese of the Catholic Church in Italy. It has been a suffragan of the Archdiocese of Milan only since 1817. Previous to the reorganization of the hierarchy in northern Italy by Pope Pius VII after the expulsion of the French and the Congress of Vienna, the diocese of Pavia had depended directly upon the Holy See, despite repeated failed attempts on the part of the Archbishops of Milan to claim control. The diocese has produced one Pope and Patriarch of Venice, and three cardinals.