Composer Samuel Bordoli presents two 'Live Music Sculptures' in London, one at Tower Bridge, the other at Monument, as part of the City of London Music Festival. At Tower Bridge, there will be a live music performance by an orchestra 42 metres above the Thames on the bridge's west walkway. The piece is repeated during the two hours and entry to the walkway during the event is free.
See also
http://www.timeout.com/london/museums-attractions/event/267767/samuel-bordoli-live-music-sculptures