Basilica di San Petronio Bologna, Italy

Begun in 1389 and never finished, San Petronio is the pride of Bologna and one of the largest churches in the world. It overlooks Piazza Maggiore in the heart of the city and contains many notable Bolognese artworks.

View of rooftops and medieval buildings, including the apse and tower of San Petronio Basilica, Azzoguidi Tower (Torre Azzoguidi or Torre Altabella), and Prendiparte Tower (Torre Prendiparte or Torre Coronata), from the terrace of Hotel Touring, Bologna, Italy. Image credit: Holly Hayes