This eye-popping Icelandic crater lake is surrounded by red volcanic rock.

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

Fittingly, America's museum of architecture is itself a magnificently designed old building.

Monasteries on rock pillars, once accessible only by frayed ropes.

The Hudson River School comes alive at this palatial estate.

The home of one of America's most wealthy industrialists is now a historic site that remembers a more decadent time in the country's history.

100 massive sculptures in the Hudson River Valley.

Oldest existing church in New York and the inspiration for Washington Irving's "The Legend of Sleepy Hollow."

The longest continuous underwater road in North America was built at the insistence of Franklin Roosevelt.

Elevated freight railway turned wildly successful urban park.

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.

The celebrated eyesore created by starry-eyed sweethearts.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

Real bones which are said to have belonged to a Polish dragon.

A painting in the historic Cathedral Basilica depicts Jesus and his disciples dining on a traditional Peruvian menu.

Huge stone depressions which may have acted as an Incan agricultural experiment.

Preserved Inca city and site of the last Inca stronghold against the Spanish conquistadors.

The mortal remains of an estimated 70,000 people lie in the basement of a monastery in Lima, Peru.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

The maze-like transportation hub contains abandoned areas, derelict stores, and a resident bat colony.

This unique exhibit "Dialogue in the Dark" reverses roles as the visionless become guides and the sighted become ‘blind.’

This daunting 1st century fortress was purportedly the site of one of the most dramatic revolts of the Jewish-Roman wars.