Palazzo Soliano, also known as Palazzo Boniface VIII, was erected by order of Pope Boniface VIII, according to some historians. Others consider it more probable that the Palace was built by the inhabitants of Orvieto in gratitude to this Pope, who withdrew from the city the papal interdict and a huge fine for damage caused by the troops of the city castles in the Val di Lago. Today the Palazzo Soliano remains the property of the Catholic Church.

A wide staircase leads to the second floor in the large room of the Palace with ten Gothic Windows, which was used as a hall for the official reception. This floor was built between 1296 and 1297 for years over a covered gallery on the first floor, the construction of which began when Pope urban IV. The tip of the Palace is crowned with battlements Guelph and decorated with a number of Windows divided by columns into two arched parts.

Today in the Palazzo Soliano is a Museum of works of art from Orvieto Cathedral (Museo Dell'opera del Duomo). Here are works from the Renaissance to the era of mannerism and the pictures painted in the 19th century. Among the artists whose work is represented in the Museum, Giovanni Lanfranco, Girolamo Muziano, Federico Zuccaro, Cesare Nebbia, Pomarancio. Special attention deserves a priceless pictures collection Ippolito Scalza and drawings Cesare Nebbia by alteration of the frescoes in the Cathedral. Mannerist sculptures of apostles and saints that adorned the Cathedral until the 19th century, are also part of the Museum's collection.

In the lower part of the Palazzo Soliano works another Museum – the Museum Emilio Greco, dedicated to the artist who worked on the great doors of the Cathedral of Orvieto. Here you can see about a hundred of his works.