Pedestrians in the German city of Nuremberg stepped aside on Sunday as hundreds of bleating sheep made their way through the downtown area on their journey to winter quarters.

Curious onlookers lined the streets, phones raised to capture the unusual sight, as the roughly 600 sheep from shepherd Thomas Gackstatter’s flock trotted past in what has become a well-loved annual event.

The animals were headed to winter pastures west of Nuremberg. During the summer, Gackstatter’s flock — along with others — helps maintain various city meadows by grazing and keeping the grass trimmed.

The 10-kilometer (just over 6-mile) route takes the flock through the city’s central market square, the Hauptmarkt, according to the German news agency dpa. Gackstatter believes Nuremberg is the only place in Germany where sheep still cross a central square. The city’s population is about 540,000.

Ahead of the procession, authorities urged residents to keep the path clear and ensure dogs were kept away from the mixed-breed flock. Drones were prohibited.

Nuremberg is not the only German city that employs sheep as natural lawnmowers; they also graze in parts of Berlin, Potsdam, Augsburg, Ulm, and elsewhere. Their slow grazing supports insect-friendly grass care, boosts biodiversity, and reduces municipal mowing costs.

For shepherds, the arrangement also provides valuable grazing land at a time when open spaces are becoming increasingly scarce.