This Manhattan skyscraper is a reminder of the brief but glorious age of urban air taxis.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

A dedication plaque on this Boston tunnel is a microcosm of a massive, controversy-laden construction project.

A gift to the children of Boston, this bronze bear represents playfulness, a spirit of love, and the warmth of big hugs.

This bronze sculpture was inspired by a photograph of Martin Luther King Jr. and his wife embracing after he won the Nobel Peace Prize.

Created by a local artist, these quirky sculptures each have their own names and personalities.

Historic home of a Black veteran of the American Revolution and one of the earliest civil rights activists in the United States.

A planet-hunting astrograph built in the 1920s to seek out the so-called "Planet X" beyond Uranus.

This Arizona observatory is famous for investigations into Martian life, and as the place humans first spotted Pluto.

The final resting place of the businessman-turned-astronomer who helped discover Pluto stands near his observatory.

Crafted in 1911, this steam locomotive spent its entire working life in Flagstaff.

This Czar-funded, onion-domed, lavishly muraled Orthodox Church played a starring role in "The Deer Hunter."

Once thought to be the fabled Holy Grail, it is now known to be an oil lamp.

Though the case is scorched and the buttons half-melted, this hardy handheld gaming device can still run a game of Tetris.

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

This memorial honors thousands of enslaved Africans and their descendants who died in colonial New York.

Pulled from the rubble of one of the worst modern tragedies, a steel crossbeam became a symbol of hope for New Yorkers.

A stone marker commemorating the first time sound was transmitted over wires.

Dedicated to a colonial woman who was hanged for being a Quaker.

The former home of a Boston physician whose murder led to a revolution in forensic science.

Former home of an abolitionist couple who escaped slavery and established the most active Underground Railroad stop in Boston.

Like stepping into a spooky fairy-tale, this shop carries the dark ideas of artists and other makers.

The monument's pointy aluminum tip has been melted down by repeated lightning strikes.

Could it have picked a better place to land?