I remember crossing a pedestrian bridge in Salzburg where there were speakers built into the structure, and it was playing Mozart’s music. In my notes from the trip in 2005, I wrote down “Makartsteg”, but I can’t find anything online to corroborate my story.
Googling indicates that the Mozartsteg and Markartsteg are separate bridges, the former built in 1903 and the latter in 2001. No mention of built-in speakers on either, though the latter does appear to have a large collection of padlocks attached to a chain-link fence.