Another Post Office Square office building is destined for cosmetic reconstruction.

LaSalle Investment Management is planning a “building within a building” at 50 Post Office Square, a 20-story building the company owns in downtown Boston. The modernization will create a new entrance at 110 High St. and include an indoor/outdoor media screen and 35-foot glass curtain addition at Congress and High. The new features are meant to enliven the ground-floor experience of the Art Deco building.

“Boston’s a target market for us. We’ve been very active here and put about $1B in investment here in the last three or four years,” LaSalle Investment Management Managing Director David Schreiber said at Bisnow’s Neighborhood Series: Downtown Boston event Thursday. “Boston is an exceptional landscape for investment right now, and that’s across all property types and all risk profiles.”

The Post Office Square building was built in 1948 as the headquarters for the New England Telephone and Telegraph Co. Elkus Manfredi Architects worked with former owner Bentall Kennedy in 2013 to reposition the tower as a Class-A office building with a modern lobby and retail. While the building is 90% occupied, including a 410K SF lease by Brown Brothers Harriman through 2028, the High Street side is largely devoid of street activity due to a blank concrete facade.

The latest chapter for 50 Post Office Square modernization comes at a time when several downtown buildings are getting face-lifts to lure more tenants. Developers have proposed a $250M recladding and expansion of One Post Office Square, home to JLL’s Boston office. Boston Properties is underway with a glass atrium addition at its nearby 100 Federal St., which will include retail, dining and a winter garden. Schreiber attributes Boston’s market conditions and price point as a driver for all the investment.

“People are often surprised when they hear Boston is one of the few major markets that is still below peak rent,” he said. “Part of what is fueling institution investment and development in Boston is there’s still quite a bit of runway in this market, which makes it really attractive for core investment and higher-risk strategies.”