Unrepaired walls from a 1920 anarchist bomb attack.

Where now stands a 42-story condominium tower of marble, glass and steel was once the central market of New York’s slave trade.

Under a glass sidewalk lie the remains of some of Manhattan's oldest buildings.

Built hundreds of years ago this downtown iron barrier once protected a much despised king.

Magnificent New Deal Murals evoke a time when New York City harbor was one of the world's greatest and busiest ports.

This Wall Street bar was once a hub of revolutionary activity where Washington famously bid farewell to his troops.

A monument to an Irish secret society thought to be responsible for a string of violent attacks in Pennsylvania coal mines.

This public park was the site of the largest civilian disaster of the Civil War.

The site of the notorious Camp Sumter Prison is now a peaceful memorial.