On your way up Via Montefeltro toward the cathedral, peek through the grate over the basement storeroom of the Palazzo dei Canonici, where sits the huge Botte dei Canonici (15th-century wine barrel), boggling the mind with its 19,350-liter (5,112-gal.) capacity. Those that would prefer to skip the climb can take the free elevator, just off Piazza Grande on Via XX Settembre (daily 10am-6pm).
The interior of the 13th-century cathedral (aka Basilica dei Santi Mariano e Giacomo Martiri) is striking for its "wagon vaulting," a receding series of pointed arches defining the graceful bulk and space of the single central nave. Most of the art on the nave altars is by local talent, including multiple works by Virgilio Nucci, Benedetto Nucci, Sinibaldo Ibi, and Antonio Gherardi. In the third niche on the right is a Pietà by Dono Doni, who also painted the Way to Calvary in the seventh niche. In between the two, the fourth niche on the right opens up to the florid baroque Capella San Sacramento (1644-72) by Francesco Allegrini and Gherardi. Don't miss the Nativity in the left aisle's sixth niche, a rare work by Giuliano Presutti.