Hotel Zanzibar was operated by human civilians in Old Mombasa on Earth. Only the first floor of the facility is ever seen, but it appears to be a run down facility.
In 2552, during The First Battle of Earth, the Hotel Zanzibar was abandoned, along with the rest of the city. When the UNSC In Amber Clad dispatched Pelicans full of relief troops for the massive battle going on inside the city, one of those Pelicans was shot down by a Scarab near the hotel. The Marines who survived the crash set up a bunker inside the hotel lobby. They were almost surrounded and overwhelmed by Covenant ground forces when the Master Chief arrived and aided the Marines, eventually leading them into New Mombasa.
The attack on the hotel was led by an Ultra Elite (Heroic and Legendary difficulties only).