Learn about "Irreplaceable America:" 10 heritage sites essential to U.S. history, facing urgent preservation challenges.

This is your first of three free stories this month. Become a free or sustaining member to read unlimited articles, webinars and ebooks. Monuments, it won’t surprise you to hear, hold immense power. The very first monument made in the United States was ...

Scientists drove ATVs for miles and then hiked miles more through dense forest to reach a site untouched by looting on Mexico’s Yucatán Peninsula. They named it Minanbé, meaning “there is no path.”