The hidden pool inside the Woolworth Building that once belonged to the building's owner and developer Frank W. Woolworth, was recently restored and unveiled this week! The pool has always been a mystery to skyscraper enthusiasts, sitting drained and abandoned for the last two decades.

The 'Cathedral of Commerce" as the Woolworth was known, was built in 1913 – at the time the tallest building in the world – for American retail giant, the F. W. Woolworth Company. When designing the tower, Woolworth and his architect Cass Gilbert planned to include a swimming pool and Turkish bath in the basement, lined with marble. Some accounts say the amenities were actually included to attract tenants to the building at a time when there was a surplus of commercial office space in Lower Manhattan, not for Woolworth's personal use. A prospectus on the building from 1913 lists the pool and bath along with the building's other features.

The 15-by-55-foot pool was drained in 1999, only to be recently restored by Alchemy Properties, who has converted the top thirty stories of the tower for thirty-three luxury residences. This week we got to visit the pool, which had just received its permits to operate.