A controversial plan to build new a new condo complex with retail space along Washington Street in Lower Mills will be delayed for at least a few months after a ruling by a city of Boston board this week found that one of the existing properties on the site may be historically significant.

The Boston Landmarks Commission, which monitors historically significant properties in the city, invoked a 90-day demolition delay at its meeting on Tuesday. The middle of the three structures currently on the lot, 1126 Washington St., “could be as old as 1750 and is likely one of 30 oldest buildings in Boston,” the Commission said in a Tweet announcing the demolition delay.

This stalls movement on a controversial proposal to construct a residential building with 57 condo units at the site, which once included the former Molloy’s funeral parlor. City Point Center, LLC, the developers, last month showed members of the Lower Mills Civic Association an alternative building plan for the site in case the three houses stay on the lot. The proposal is still under review by the Boston Planning and Development Agency.