Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

A self-built castle made by a mysterious man.

This striking public art installation is suspended above a public park, designed to gently move in the breeze.

The installation’s official name, “You Who Are Getting Obliterated in the Dancing Swarm of Fireflies,” says it all.

A geological mystery on Camelback Mountain.