7 Yerba-Buena Tunnel
Bay Area, California
I must have driven through this tunnel between Oakland and San Francisco hundreds of times and never noticed how freakin’ huge this thing is. At 525 feet long, it’s still the largest single-bore tunnel in the world and was finished all the way back in 1936 when I’m pretty sure they had to dig it out with pick axes and willpower. Fun fact: apparently it was cheaper to dig through the island than to just build a giant bridge connecting either side of the bay.