A glimpse into early 19th-century education.

An aptly-named street near the birthplace of the modern LGBT rights movement.

An oft-overlooked, magically musical monolith that stands majestically between Arlington Cemetery and the Iwo Jima Memorial.

Fake subway tiles were installed to cover a design that resembled the Confederate flag—it's unclear if the resemblance was intentional.

An unassuming secret door once led to a legendary watering hole.

A mosaic made of materials gathered from this Brooklyn community adorns the walls of this tunnel.

The ballpark in "Pigtown" where the Brooklyn Dodgers made their name was replaced with a huge apartment complex.

19th century cemetery hidden in Brooklyn's Prospect Park.

This elaborate tunnel is the first structure composed of cast concrete in the United States.

A tree that grows parallel to the ground was declared Brooklyn's "crowning curio" by the poet who saved it.

You can still ride this 100-year-old work of art in Brooklyn's largest public park.

The site of a fallen tree that protected Americans from British forces during the American Revolution.

This secluded ruin was once a home for exotic plants.

This striking arch, one of the first architectural elements constructed in Prospect Park, was recently restored to its original glory.

Once the tallest building in the world and the site of "the highest dinner ever held in New York" this building now holds the most expensive penthouse in the city.

The site of the deadly Triangle Shirtwaist Factory Fire.

A trove of century-old litho stones from the Puck Building's printing days were discovered behind a cellar wall, and are now hanging in the store.

Plot your trip through the city on the sidewalk.

These historic buildings once housed the headquarters of one of the most infamous gangs of New York.

The artist and New York City icon lived, worked and died in this converted carriage house owned by another iconic artist, Andy Warhol.

New York City's only preserved family home from the 19th century.

This exemplar of modernist architecture is meant to captivate and inspire students of the Cooper Union.

This 220-year-old house is a reminder of New York City's Dutch past.

The place where Dvořák composed some of his most famous works.