When it opened in 1843 the Thames Tunnel was described as the Eighth Wonder of the World. People came from far and wide to see the first tunnel under a river. On the first day, fifty thousand people descended the staircase and paid a penny to walk through the tunnel. By the end of the first three months there were a million people, or half the population of London. This was the most successful visitor attraction in the world. In the age of sail and horse-drawn coaches, people came long distances and bought souvenirs and listened to the entertainment in the cross-tunnel arches. The idea, of course, was not entertainment but to move cargo and turn a profit.