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.