From atop a hill at the center of Cape Town, a cannon has been signalling the time since 1806.

The Cape of Good Hope is not quite as low as you can go on the African continent, but it's still geographically significant.

The first museum in the United States dedicated entirely to posters.

The former hotel where Tesla invented the radio.

The one-time epicenter of American songwriting is now a little remembered Manhattan commercial block.

A vibrant, 100-foot-tall mural dedicated to Evelyn Nesbit, the tragic icon of the Gilded Age.

This monument to a veteran of the Mexican-American War is one of only two in Manhattan that serve as an actual mausoleum.

A Manhattan courthouse hides a small but scathing memorial to Holocaust injustice.

A 19th-century politician who died after walking home in a blizzard is honored with this Manhattan statue.

Once an opulent Art Nouveau hotspot, the Constanța Casino is one of Romania's most beautiful abandoned buildings.

This communist behemoth is the heaviest building in the world and a legacy of a brutal regime.

Grand Orthodox cathedral with walls filled with frescoes and icons.

A striking symbol of the Bulgarian capital.

Climb a set of vertiginous stone steps to the top of this impressive ancient edifice.

No one is sure if the world's fourth-largest diamond had been found in a rubbish heap or was pawned by Napoleon's mom.

The most metal church of all time was built in record time because of an international, pious pissing contest.

A fountain standing as a testament to a doomed alliance.

Ancient serpentine sacrifice holder that has stood the test of time.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

A marvel of Byzantine engineering under the streets of Istanbul.

A historic 1890s architectural masterpiece with an iconic clock tower that, once open to the public, now faces an uncertain future.

A tiny museum housed in a New York freight elevator specializes in the "overlooked, dismissed, or ignored."

An uber-secure, windowless tower of doom in the center of Manhattan is an NSA spyscraper.

This lovely, if imposing, piece of Canadian gothic is possibly the most photographed hotel in the world.