In September 1666, a great fire swept through London, destroying the city. But after the fire, London was reconstructed on essentially the same medieval street plan, which still exists today.
Christopher Wren, one of the greatest architects of the time, is responsible for rebuilding 52 churches in the City of London after that fire. That includes St. Paul's Cathedral, which is widely considered to be his greatest work.
One day in 1671, Wren observed three bricklayers working on the Cathedral. One was crouched, one half-standing, and one standing tall – working hard and very fast. Wren asked each bricklayer, “What are you doing?”
