Granted, when most people hear the phrase “Bridge of Sighs,” they think of the famous landmark in Venice where prisoners were sent to confinement. Some, who’ve read either Upton Sinclair’s The Jungle or Erik Larson’s The Devil in the White City, might think of ramps at the pork slaughterhouses in Chicago. The newly divorced in Reno even use it to describe the Virginia Street Bridge, where wedding rings can be discarded into the river after a quick divorce. But to a certain demographic, “Bridge of Sighs” means the kickass 1974 album by guitarist Robin Trower, who plays on Wednesday, March 2, at the Mystic Theatre. 21 Petaluma Blvd. N., Petaluma. 7:30pm. $26-$29. 707.762.3565.