After more than two decades in the making, the Marriott Marquis, Washington D.C. opens for business Thursday at noon. The $520 million hotel, which has an underground connection to the Walter E. Washington Convention Center, is the District’s largest hotel, with 1,175 rooms and 83 meeting spaces.

On Wednesday afternoon, less than 20 hours before it was to open, dozens of employees made last-minute updates. Some polished the banisters while others stocked the sports bar. “We’re in the final stretch,” said William C. Wallace, the hotel’s director of sales and marketing.

An early look at Washington’s convention center hotel: