The Museo dell’ Opera del Duomo was formed in 1882 and moved to Palazzo Soliani in 1897.  This closed in 1989 and the collection was inaccessible to the public for a considerable period.  It was laid out in the first floor of the Palazzi Papali and opened to the public in 2006.  
                  
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                      ✴The ticket office and the first room of the museum, the Sala degli  Affreschi are in the room above the old episcopal library. 
 
 
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                      ✴The Sala della Maestà (Room II)  is at the top of the entrance staircase. 
 
 
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                      ✴Room III is in a space sometimes referred to as the chapel of the palace of Pope Martin IV;
 
 
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                      ✴Room IV is in the main room of this palace; 
 
 
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                      ✴Room V is in the palace of Pope Nicholas IV; and 
 
 
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                      ✴the Sala delle Sinopie (Room VI) is in the palace of Pope Urban IV.