Sequoia Tree Tunnels

Sequoia National Park, California The iconic Wawona Tree tunnel may not be standing anymore it finally collapsed during an especially rough winter in 1969 after, uh, 2,100 years but you can still squeeze through the fallen Tunnel Log in Sequoia National Park in central California. An 8 foot tall tunnel bored through the body of a 2000 year old tree may not be one of the most daring feats of engineering on our list, but it gets bonus points for making you grapple with your own mortality.