The portico that connects the city to the Sanctuary of the Madonna di San Luca on Colle della Guardia is, at 3.796 kilometres and 666 arches, the longest covered walkway in the world. It was built between 1674 and 1793 in stages, funded by hundreds of private donors whose names are inscribed on individual arches and chapels along the route.
The walk takes about an hour going up and forty minutes coming down. The first kilometre from Porta Saragozza is essentially flat and runs through residential streets; from the Arco del Meloncello the portico starts climbing in a serpentine that rises 280 metres in 1.7 kilometres. UNESCO listed the porticoes of Bologna in 2021 — including San Luca — as world heritage.