Liberty Mutual is planning a significant expansion of its headquarters in Boston’s Back Bay neighborhood, committing to a large-scale construction project amid a sluggish urban office market and ongoing shifts toward remote work. The insurance company aims to consolidate its employees and operations into a single centralized location, signaling confidence in the long-term prospects of its downtown presence.

In a letter submitted to the Boston Planning Department earlier this month, Liberty Mutual outlined its proposal to expand its existing headquarters at 157 Berkeley Street. The plan involves demolishing three adjacent brick buildings to make way for new construction that includes a “vertical addition” to an existing wing of its 22-story tower, as well as a new 10-story building at the corner of Stuart Street and Columbus Avenue.

The expansion will fully occupy a notable triangular parcel across from what was formerly known as Castle at Park Plaza. Liberty Mutual also indicated it might install a prominent corporate sign visible from across the Back Bay skyline as part of the development.

“This project is designed to create a workplace for the next 100 years,” said company spokesperson Glenn Greenberg, emphasizing the firm’s intention to bring all of its employees and facilities into this single expanded block over the coming years.

The proposal reflects Liberty Mutual’s willingness to invest heavily in its Boston headquarters despite ongoing challenges facing downtown office occupancy, including declines in commuter traffic and widespread adoption of hybrid and remote work models. The company’s plan underscores a strategic commitment to maintaining and growing its presence in one of Boston’s key commercial districts.