Gregg Bernstein drew his inspiration for a new mural he’s painting this week in Lower Mills from an old postcard. Bernstein, the man behind many of Boston’s largest and most celebrated wall murals, has been commissioned to paint the scene by the owners of The Sweet Life, a restaurant and café that opened at the corner of Richmond Street and Dorchester Ave. in September.

Bernstein is not sure of the precise date of the postcard, but he says it depicts Lower Mills during the hey-day of the Walter Baker Chocolate Factory in the early 20th century.

“There is a boxy-looking streetcar in the image. I’d say it’s about 100 years ago. The buildings all look the same, though, which is really cool.”

Bernstein says the new mural will take between 4-5 weeks to complete, weather permitting. The building itself is made of brick, but the north facing wall he’s painting is covered in a stucco finish, which he says is “really nice and smooth. It has a little tooth to it and it helps pick up the texture. It’s really great.”

The blog Lower Dot has another photo of the mural in progress that shows the full view and the rich colors that are developing.