The bridge crosses from the Doge's Palace to the prison.
The prison is connected to the Doge's Palace by the Bridge of Sighs which is just above the prion in the image.
The Bridge of Sighs (Italian: Ponte dei Sospiri) is a bridge located in Venice, northern Italy. The enclosed bridge is made of white limestone and has windows with stone bars. It passes over the Rio di Palazzo and connects the New Prison to the interrogation rooms in the Doge's Palace. It was designed by Antoni Contino (whose uncle Antonio da Ponte had designed the Rialto Bridge), and was built in 1602.