As one of a series of April Fool’s jokes in the 1840s, the Boston Post once announced that a cave full of treasure had been discovered beneath Boston Common. Workmen removing a tree reportedly found a stone trapdoor that led to a cave full of jewels, coins, and jeweled weapons. You might think Bostoners would be too cynical to accept this, but apparently a mob formed:

It was rainy, that 1st of April, the Legislature was in session, and it was an animated scene that the Common presented, roofed with umbrellas, sheltering pilgrims on their way to the new-found sell. A procession of grave legislators marched solemnly down under their green gingham, while philosophers, archaeologists, numismatists, antiquarians of all qualities, and the public generally paid tribute to the Post‘s ingenuity.

They found nothing, of course. “Man is a credulous animal, and must believe something,” wrote Bertrand Russell. “In the absence of good grounds for belief, he will be satisfied with bad ones.”