#41: Colossal Columns
Located in Japan, the name of this is an absolute mouthful. I’m not sure if megalophobes are also scared of big names, but this is The Metropolitan Area Outer Underground Discharge Channel, and it’s an underground water facility. In fact, it’s the largest one globally and keeps Japan from flooding during heavy rains.

It cost over $2.6 billion to construct and took 13 years to complete. It’s located 164 feet underground and is just over 4 miles long. It’s free to visit, but only 50 people are allowed inside at a time, and it’s closed on Mondays and major holidays. Be sure to call ahead and make a reservation – if you’re up to it!