The Polo museale of Palazzo dei Priori is located inside the homonymous thirteenth-century palace that overlooks Piazza del Popolo. The palace, the result of annexations of a private residence and the ancient church of San Martino, assumed its current appearance only in the sixteenth century with the imposing staircase and the imposing bronze statue of Pope Sixtus V, cast in 1588 by Andrea Sansovino when Fermo became an archdiocese.

Inside, the Civic Art Gallery, the Hall of the World Map, and the Reception Halls are hosted, including: the Hall of Portraits, the Hall of Costumes, the Hall of Coats of Arms, the Mayor's Hall, the Eagle Hall with the precious frescoes by Pio Panfili, and the Red Hall. 

The Civic Art Gallery houses an important collection of paintings from the Marche and Veneto schools, along with stone artifacts, costumes, coats of arms, porcelain, furniture, and precious objects. Among the most significant works are those by Andrea da Bologna, Francescuccio di Cecco Ghissi, Jacobello del Fiore (Stories of Saint Lucia), Vittore Crivelli (Crucifixion), Vincenzo Pagani, Giuliano Presutti, and Giovanni Lanfranco (Pentecost). Of particular interest is a Flemish tapestry designed by Giusto de Gand and the painting by Peter Paul Rubens depicting The Adoration of the Shepherds, commissioned by the Filippini Fathers for their church in 1608. Also included in the art gallery tour is the precious Hall of the World Map commissioned by the Fermano Cardinal Decio Azzolino and built in 1688 by the architect Adamo Sacripante, which houses the oldest part of the library. The room, fully furnished with walnut wood shelves, houses part of the ancient collection of the Municipal Library mainly donated by the Fermano Romolo Spezioli, personal physician of Queen Christina of Sweden. The imposing globe, created by the geographer Silvestro Amanzio Maroncelli in 1713, dominates the room.