Pierre Charles L'Enfant (2 August 1754 – 14 June 1825) designed the street plan of the Federal City in the United States, now known as Washington, DC. Born in France, he came to the American colonies as a military engineer with General Lafayette and became closely identified with the United States, adopting the name Peter. He was wounded at the siege of Savannah in 1779, but recovered and served in General Washington's staff for the remainder of the Revolutionary War.

Following the war, he achieved some fame as an architect by designing Federal Hall in New York City. Shortly thereafter, he entered a competition for the design of a new federal capital and won the competition, and the layout was begun in 1791.

Because of his irascible personality, L'Enfant's plan for the Federal City was only partially executed during his lifetime. He was dismissed from the execution of the project, and in anger, took his drawings with him. But much of the plan was reproduced from the memory of Benjamin Banneker, a mathematician, who was working with surveyors Andrew and Joseph Ellicott. Because of this he was never paid, and fell into disgrace, spending much of the rest of his life trying to dun Congress for payment. He was offered a position as Professor of Engineering at West Point in 1812 but declined. L'Enfant died in poverty and was buried at the farm of a friend in Prince George's County, Maryland.

In 1901 the McMillan Commission rediscovered the layout and used it as the cornerstone of its 1902 report, which laid out a plan for a sweeping National Mall. His adopted nation finally recognising his genius, L'Enfant was reinterred in Arlington National Cemetery with a ceremony at the Capitol Rotunda in 1909 and honored with a monument at his grave in 1911.