Every year model trains zip through a miniature New York City that's now 150 landmarks strong.

This former crime corner has been turned into an eclectic community center.

The notorious headquarters of a corrupt political machine.

Salute the leader of the proletariat.

America's oldest Eastern European synagogue provided the immigrants of crowded Lower East Side tenements a space of sanctuary.

Empty, but not abandoned, this cavernous Brooklyn loading dock was once considered the largest individual building in the world.

A discreet little stairway on St. Nicholas Avenue leads to a quaint and unexpected cobblestone street of 19th century wooden rowhouses.

Visit the monolithic tomb of America's most famous general.

Once America's longest-manned military fort, now an abandoned hulk.

Just your average Marie Antoinette–themed speakeasy in an abandoned 19th-century subway tunnel.

Nikola Tesla's former home contains an homage hidden from plain sight.

Read between the lines of the subway map to find the hidden abandoned Civil War fort.

Sniff the Titan Arum's rotting flesh.

Scars of this building's past life as a violent prison still cover its walls.

This ominous Albanian fortress houses tanks and downed planes as a reminder of their victories over Western imperialism.

The ruins of this ancient fortification wall sit in the middle of a quiet, residential intersection.

A 19th century artistocrat's mansion, turned into a library, hidden in a modern library.

Hideout of thieves, monks, and goat-footed gods.

One of Frank Lloyd Wright's greatest—and favorite—architectural masterpieces was almost lost.

A gothic church spire sits atop this skyscraper, the tallest church in the world.

A chapel built by Italian POWs during World War II tells a forgotten tale of the war on the home front.

In Hong Kong, a fairytale flower tunnel is hidden within the gardens of a public housing complex.

This hulking behemoth is actually five interconnected towers built in the 1960s.

About as hidden as can be, this specialty coffee shop is wedged between multi-story buildings at the end of a dark, skinny alleyway in Seoul.