There used to be an actual wall at Wall Street, in the city that was called New Amsterdam.
Dutch settlers in the 1600s erected the wall to protect against natives, wild animals, and those pesky British fleets that wanted to land.
Alongside the wall ran a dirt road, aptly named Wall Street.
Of course, a wall made of wood didn’t hold out the British for long. They tore down the wall, used it for firewood, and renamed the city New York.
Under British rule, the road became a major thoroughfare, and the name stuck.