In the early 20th century, a hulking, somewhat ominous molasses storage tank loomed over Boston. It was notoriously leaky—local children would often collect stray molasses drippings in a pail and bring the sweet stuff home to their families. And on a warm January day in 1919, disaster finally struck: the tank burst and 2.5 million gallons of warm, sticky molasses escaped, forming a 30-foot wave that traveled at 35 miles per hour. This molasses tsunami flattened buildings, knocked out the steel supports for an elevated train, killed 21 people, and injured more than 100. Many bodies were found during the cleanup, which took months and involved salt water, saws, and industrial-strength brooms. Local Bostonians today say you can still smell molasses on a hot day in the north end, an entire century later.