There's nothing hidden about the National Aquarium, a waterfront gem in downtown Baltimore that draws more than a million visitors a year and was recently lauded as the city's best attraction.
But a little more than a mile away -- hidden in plain sight in Baltimore's Fell's Point neighborhood -- is the aquarium's secret support facility, a sprawling building that workers simply call The Warehouse.
The building houses the institution's Animal Care Facility and other support operations like a fabrication lab, a wood shop, storage rooms and offices. While The Warehouse is not open to the public, HuffPost Travel recently took a backstage tour to explore the efforts and equipment necessary to run one of the world's biggest aquariums. For starters: plumbing, lots of plumbing.