For years, East Boston residents walking the Mary Ellen Welch Greenway passed a lonely sight — a bright blue train car sitting empty, tagged with graffiti, a relic of a forgotten era.

Now, that caboose is serving cold brew and ice cream.

The Blue Caboose, opened June 3 by local entrepreneurs Troy Retzer and Liz Kelley, is a full ice cream and coffee shop operating inside a restored 1940s-era train caboose. It took five years to get from “what if” to opening day.

Retzer first approached the City of Boston in 2021 about turning the city-owned caboose into a business. He and Kelley won the rights through a public bidding process. What followed were years of permitting, construction delays, and infrastructure headaches — the train car was dilapidated inside, with bunk beds, the original steel stove, and layers of graffiti.

“It was just a lot of figuring things out as we went,” Kelley said.

Kelley — who also owns Travel Mug Cafe — kept the project alive. She called The Blue Caboose “the little engine that could.” By the time they announced the project on Instagram in April 2023, the community was hooked.

When they finally opened — with just a day’s notice on Instagram — the line stretched down the block. They sold 350 ice cream cones on day one. “The support around the community and just seeing how excited everyone is for it has just been unbelievable,” Retzer said.

The Blue Caboose serves Travel Mug Cafe’s cold brew, matcha, and iced tea alongside ice cream sundaes and chipwiches. Flavors include black bear, coffee cookies and cream, and salted caramel chocolate pretzel.

Kelley and Retzer are planning a grand opening with Mayor Michelle Wu in the coming weeks. A larger celebration will wait until construction wraps on the surrounding greenway, which will add benches, cafe-style seating, and a community garden near the caboose.

Find it: On the Mary Ellen Welch Greenway, East Boston waterfront.

Follow them: @the.blue.caboose on Instagram