Did you know that the Hoover Dam contains enough concrete to pave a 16-foot-wide road from San Francisco to New York City? Built in the 1930s, this massive structure required over 3.25 million cubic yards of concrete. To prevent cracking during the curing process, engineers ran a network of pipes through the dam to circulate ice-cold water. This innovative technique cooled the concrete in just a few years—otherwise, it would have taken over 100 years to fully harden!