When school is out for summer and the campus is emptied of students, it could happen – and does – that music would flow into the vacuum, calling people back that they might give a listen to music. This is what’s happening at the Complutense University now. With its 86,000 students gone for vacation, the university’s Alfonso XIII Royal Botanical Garden is converted to an open-air auditorium during the warm and fragrant nights. Forget the classrooms! Let the music flow. Rock. Soothe. Vibrate.