Houston First Corp., which manages the George R. Brown Convention Center and several other public facilities in the Texas city, has issued a request for proposal, looking for a firm to develop and design a hotel that to be built on top of the new parking garage and office building planned just north of the center. The property, which could be as large as 400 rooms, would be connected to the facility by skybridge. HFC would like construction to begin around September 2015. Meanwhile, construction began in April on the 1,000-room Marriott Marquis Houston. The headquarters hotel, on target to open in 2016, also will be connected to the convention center.