This elaborate towering structure was once famed for its revolutionary height.

This splendid Versailles-inspired mansion has the largest French-style formal gardens in North America.

In this cemetery stands the country's first public crematorium.

Now a retreat center for the faithful, it once provided training for clergy—but it began as a farm owned by a famed financier and his opera singer wife, who built a surprise in the backyard.

Home of Philip Johnson, one of the 20th century's most influential architects.

An Escher-inspired library dedicated to the wonders of the human mind, yet closed to the public.

A gorgeous medieval library where the books are kept in chains.

This domed temple was built in a hidden cave mouth as a refuge for sinners seeking absolution.

A tiny chapel perched along a 14th-century bridge.

Though much of the castle was robbed of its stones, the underlying earthworks are among the best-preserved in England.

The tallest freestanding structure in the United Kingdom.

One of the first big sculptures anywhere in Australia.

A once-thriving hotel in the Swiss Alps couldn't compete with climate change.

Don't blink or you'll miss it.

Trek up this glacier before it disappears.

Unable to build support structures on glaciers, the engineers for this tramway were forced to design a unique system.

This "preacher's pulpit" once used for pagan ritual, is home to a new, and dangerous ritual.

The hike through a narrow river flanked by the 2,000-foot-tall walls of Zion Canyon is one of the best in the world.