William Penn learned many lessons in life. Living in 17th century England taught him that open space offered breathing places for great cities and also slowed the spread of fire.
He applied what he had learned to Philadelphia. He insisted on a site that was "navigable, high, dry, and healthy." He wanted "uniform" streets with "houses built in a line." He envisioned "gardens, orchards, or fields" around the houses. Penn wanted "a green country town which will never be burnt, and always be wholesome."
Penn's city plan, drawn up by surveyor Thomas Holme included five public squares, the center one for "houses for Publick affairs" and the others as green oases carefully placed throughout the developing city.