In 1682, William Penn sought to map out his vision for Philadelphia. He appointed Thomas Holme — a former captain in the English army under Oliver Cromwell — as Pennsylvania's first surveyor general, and handed him the task.

Throughout the 17th century, Europe's great cities were ravaged by disease and fire. The Great Fire of London virtually destroyed England's capital city in 1666, and the bubonic plague was endemic throughout much of Europe during the time period.

Keenly aware of the factors that contributed to these urban hazards, Penn endeavored to make Philadelphia a "greene country towne" with large plots for homes spacious enough for personal gardens and green spaces scattered throughout the city. Following Penn's wishes, Holmes laid out five parks — including what is now known as Washington Square — in his 1683 plan.

Philadelphia developed much differently than how Penn had hoped. The city became a dense metropolis, home to America's largest urban population during the Revolutionary period.

Originally part of Penn's open and verdant design, Washington Square followed a divergent trajectory, like the rest of the city. During the 18th century, the square was primarily used as a potter's field where the city buried the bodies of the unknown dead.

The square continued to serve a similar function during the Revolutionary War. Either stricken with disease or injured in combat, countless soldiers from the Colonial Army perished in the Philadelphia Hospital and Bettering House for the Poor. Many were interred in the square, situated nearby.

On April 13, 1777, John Adams wrote a letter detailing the square's macabre aura:

"I never in my whole life was affected with so much melancholy. The graves of the soldiers, who have been buried, in this ground, from the hospital and bettering-house, during the course of last summer, fall and winter, dead of the small pox and camp diseases, are enough to make the heart of stone to melt away!"

During the British occupation of Philadelphia, the bodies of Colonial Army prisoners starved or beaten to death in the Walnut Street Jail were also buried in the square. When the Colonial Army retook the city in 1778, many British guards met a similar fate.

After the turn of the century, the square finally lived up to the intent behind its creation. The space was redeveloped and — in 1825 — renamed Washington Square in honor of George Washington.

Prominent Philadelphia architect William Strickland drafted a plan to create a monument in Washington's honor. The public admired the grandeur of the design, and a cornerstone was ceremoniously placed in late February 1833.

Strickland and the city, however, would never actualize the monument, as Philadelphia and the rest of the country contended with the financial crisis of the late 1830s and the nation's capital became the favored spot for the construction of grand national monuments.

Over the next century in Philadelphia, the city would gradually beautify the space more and more, adding benches, promenades, and lampposts. In 1954, the city chose to construct a monument to commemorate the sacrifices of the Colonial Army. To pay homage to the average soldier, the monument's committee enlisted the help of archaeologists, who dug in the northwest section of the square and uncovered the remains of an unknown individual killed by a head wound caused by a musket ball.

The city reinterred the body beneath a statue of George Washington, behind which rests a wall that reads: "Freedom is a light for which many men have died in darkness."

Instead of memorializing a single historical figure, the Tomb of the Unknown Revolutionary War Soldier acknowledges the contributions of common Americans, a fitting framework considering Washington Square's history as a resting ground for multitudes of anonymous people who helped set the course for the United States.

Patrick Glennon is a communications officer at the Historical Society of Pennsylvania. pglennon@hsp.org