This frozen tunnel in central Alaska is both an engineering feat and a valuable climate classroom.

An artsy hidden staircase leads to breathtaking views of San Francisco.

View the California coastline (and the home of Barbara Streisand) inch by inch with stunning, government-sanctioned aerial photography.

Happy harbor seals frolic and snooze on this warm, sandy stretch of coast.

From Japan to Italy, this California park explores the world's cultures through their gardens.

The White House Situation Room was taken apart in 2006 and shipped to the Ronald Reagan Presidential Library.