Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C. is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution. The federal district is therefore not a part of any U.S. state. It was formed from land along the Potomac River donated by the states of Maryland and Virginia; however, the Virginia portion was returned by Congress in 1846. A new capital city named after George Washington was founded in 1791 to the east of the preexisting port of Georgetown. Congress consolidated the City of Washington, Georgetown, and the remaining unincorporated area within the District under a single government in 1871.
Washington, D.C., is a planned city. The design for the City of Washington was largely the work of Pierre (Peter) Charles L’Enfant, a French-born architect, engineer, and city planner who first arrived in the colonies as a military engineer during the American Revolutionary War. In 1791, President Washington commissioned L'Enfant to layout the design of the new capital based on plans of cities such as Amsterdam, Paris, Frankfurt, Karlsruhe, and Milan brought from Europe by Thomas Jefferson in 1788. The L'Enfant Plan for Washington was modeled in the Baroque style and incorporated avenues radiating out from rectangles, providing room for open space and landscaping. L'Enfant's design also envisioned a garden-lined "grand avenue" approximately 1 mile in length and 400 feet wide in the area that is now the National Mall.
In March 1792, President Washington dismissed L'Enfant due to his insistence on micromanaging the city's planning, which had resulted in conflicts with the three commissioners appointed to supervise the capital's construction. Andrew Ellicott, who had worked with L'Enfant surveying the city, was then commissioned to complete the plans. Though Ellicott made revisions to the original plans, including changes to some street patterns, L'Enfant is still credited with the overall design of the city. The City of Washington was bounded by what is now Florida Avenue to the north, Rock Creek to the west, and the Anacostia River to the east.
By law, Washington's skyline is low and sprawling. The first building height restrictions in D.C. were put in place in 1894. The Heights of Buildings Act of 1910 amended the restrictions to allow buildings that are no taller than the width of the adjacent street, plus 20 feet. Despite popular belief, no law has ever limited buildings to the height of the United States Capitol or the 555-foot Washington Monument, which remains the District's tallest structure.
The District is divided into four quadrants of unequal area: Northwest (NW), Northeast (NE), Southeast (SE), and Southwest (SW). The axes bounding the quadrants radiate from the U.S. Capitol building. All road names include the quadrant abbreviation to indicate their location, and house numbers are assigned based on the approximate number of blocks away from the Capitol. In most of the city, the streets are set out in a grid pattern with east-west streets named with letters (e.g., C Street SW) and north-south streets with numbers (e.g., 4th Street NW). Some Washington streets are particularly noteworthy, such as Pennsylvania Avenue, which connects the White House with the U.S. Capitol, and K Street, which houses the offices of many lobbying groups. Washington hosts 176 foreign embassies, many of which are located on a section of Massachusetts Avenue informally known as Embassy Row.