Neighbors out for essential errands and shelter-in-place strolls are likely getting tired of seeing the same surroundings every day. 

So a group of San Francisco historians is finding a way to brighten their days: posting printouts of historical photos of the city, at the same intersections where they were once taken. 

The guerrilla poster project is being spurred by OpenSFHistory, a collection of nearly 50,000 historical images of the city that were donated to the Western Neighborhoods Project (WNP).

Best of all, anyone can participate: an online map lets you search for your street, then print out vintage photos of nearby intersections to tack or tape to telephone poles. The posters have information on when the photo was taken, and a QR code to learn more about each photo's history and context online.

The OpenSFHistory collection includes photographs from the 1850s through the 1970s. They spotlight infrastructural improvements, residential and commercial architecture, the fallout from the 1906 San Francisco earthquake and fire, prominent San Franciscans and informal street scenes and snapshots of daily life.

The idea for posting them outdoors was entirely grassroots, said David Gallagher, a WNP director. In a blog post, he explained that he got the idea when he saw Twitter posts of photos from the collection printed out and posted in windows and on telephone poles.