Aztec Ruins National Monument

Despite the name, these great stone ruins near Farmington, New Mexico were built not by Aztecs but by the Ancestral Puebloans in the 1100s, part of the Chacoan world; the West Ruin's Great Kiva, a 48-foot-wide ceremonial chamber, has been fully reconstructed so visitors can step inside.

Walk through doorways 900 years old, duck through the rooms, and step inside the reconstructed Great Kiva; young kids can earn a Junior Ranger badge. For a challenge, study the original timber roofs, rare surviving wood from Chacoan builders, and the site museum's excavated treasures.