Secret

A subterranean shelter remains intact under a busy Paris railway station.

A distillery built on (and above!) mobster Dutch Schultz's Prohibition-era underground moonshine business.

No one knows who painted this mysterious mural in a Penn State basement.

The laboratory where the Soviet secret police invented exotic poisons used to kill dissidents in hideous and (mostly) untraceable ways.

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

A double agent hid information for the Soviet Union beneath this bridge for more than 20 years.

The beautiful tunnel that ran from the lobby to Penn Station is still hidden underneath 34th Street.

This historic church is named for abolitionist Henry Ward Beecher and the ruse to arm his fellow abolitionists.

A 500-year-old series of tunnels long believed to be folkloric was uncovered beneath the streets of Puebla.

One of the now-less-hidden floral gems of the "Emerald Necklace."

There are hundreds of secret WWII bases hidden in British forests. Built to fight a Nazi invasion, they remained unknown for decades.

For centuries no one knew there were hundreds of bones and precious artwork hidden beneath this Swiss church.

It took over 100 years to decode this enigmatic epitaph for two buried brides.

A secret hatch containing two parchments was discovered in this statue over 40 years after its installation.

A cheeky architectural easter egg.