Brookfield Properties plans to renovate and rebrand 51 Sleeper St., the eight-story waterfront office building at the entrance of Boston’s Seaport District that Brookfield acquired earlier this year for $91 million.

Brookfield is renaming the eight-story, 152,000-square-foot office “Three Seaport.” Merge Architects of Boston designed a redevelopment that includes a revamped lobby and ground-floor entrance as well as a new roof deck.

“When it’s a nice day, having a roof deck is a real…

Boston Biz Journal