Milwaukee-based hotel development firm Jackson Street Holdings LLC will convert the Commerce Building near the downtown Milwaukee convention center into a 150-room SpringHill Suites by Marriott hotel. The hotel will open in 2016. It will have 2,000 square feet of meeting space and a restaurant, according to the firm’s website. In December, Jackson Street Holdings purchased the six-story, 92,255-square-foot office building and a two-story parking structure, both built in 1927, from Zilber Ltd. for $4.5 million, according to state records. The building is located across the street from the Wisconsin Center and is connected to the facility via skywalk.