Mike Ritter moved to Boston in late 2002 and has been exploring ever since. He started Ritterbin Photography in 2005 and has done work for organizations and foundations like the Martin Richard Foundation, Goodwill, Greater Ashmont Main Street, Citizen Schools, the Boston Book Festival, among others.

Now, Ritter’s “time collage” photography series from his ongoing historical project called Boston Cornerstones is being showcased in City Hall’s Mayor’s Gallery through Fri., Dec. 29.

A “time collage” is a handful of shots from the same vantage point with a cornerstone visible somewhere in the frame, according to Ritter. Later, he blends them together to build layers and meaning into one final image.

The photos showcased in the Mayor’s Gallery each come with their own write-up, including the year of the building in the image, the date and time the images were made, and the context of what’s happening in the shot.

“The Boston Cornerstones project presents me with a cohesive way to document the city’s architecture, institutions, residents, culture, politics, traditions, weather, and current events as they turn into the past,” said Ritter, 37. “I can see myself doing this for a long, long time because each image ties back into others and they tell Boston’s story in a multi-faceted way.”

As a photographer, Ritter has traveled all over the world, but soon realized all the work he needed was in his backyard.

“I know Boston offers more than enough for me to explore with my camera. I take lots of pride in the fact that my business is located in Dorchester and the majority of my work is with Boston clients,” said Ritter. “Boston has been very good to me and I hope to continue paying it back.”

Ritter’s website, bostoncornerstones.com, displays all the cornerstones he’s found on a map and you can search by date and neighborhood, but it’s also an interactive experience where you can share your stories of certain buildings and the cornerstones you’ve found. He urges the public to head over to that website and share the cornerstones they know that may not be listed. He wants to tell a grand narrative about the city, but knows that story will only get better with the help of others, so go share your stories.

“In the end, this is a celebration about the passage of time and Boston, and we all know celebrations only get better when more people are involved,” said Ritter.