Madonna di San Luca, Bologna

The Sanctuary of the Madonna of San Luca is a basilica church located in Bologna, northern Italy, situated atop the forested hill of Colle (or Monte) della Guardia, approximately 300 metres above the city plain, just southwest of the historical centre. Although a modern road leads to the sanctuary, it is more traditionally accessed via a 3.8 km-long monumental portico consisting of 666 arches, constructed between 1674 and 1793. This covered arcade, part of the Porticoes of Bologna UNESCO World Heritage Site, was originally designed to shelter the annual procession of the sacred icon of the Virgin Mary from the cathedral in central Bologna to the sanctuary. Many of the arches were originally sponsored by prominent families, and some included icons or small chapels.

Church data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).