Port-Aviation was an airfield in the commune of Viry-Châtillon in Seine-et-Oise (now in Essonne), France. It operated as a popular air racing and aviation exhibition venue and hosted civilian flight schools from its opening in 1909 until the start of World War I in 1914, then as a training center for military pilots during the war. Situated on land prone to flooding, it closed in 1918. In its earliest years it was an internationally important aviation center. Although designed as an aviation event venue rather than as a true airport or aerodrome, Viry-Châtillon claims for it the title of "world's first organized aerodrome."

Although Port-Aviation was located entirely within Viry-Châtillon rather than on the territory of either Juvisy-sur-Orge or Savigny-sur-Orge, the press and post card publishers habitually – to the consternation of the civic leaders of Viry-Châtillon – referred to it as Juvisy Airfield (or variations such as Juvisy Aerodrome or simply Juvisy) or sometimes as Savigny Airfield because the Juvisy and Savigny-sur-Orge railroad stations served it; in fact, a sign at Juvisy station referred to Port-Aviation as "Juvisy Airfield." As a result, the airfield often is referred to as "Juvisy Airfield" by historians and the general public.

Port-Aviation was the site or origin of many record-breaking or otherwise historic flights and aerobatic feats, and a number of aviation firsts took place there, such as the first air race, the first flight with two passengers, and the first inverted airplane flight, as well as only the second aerobatic loop in history. The first airplane with a tubular fuselage, the first flying boat, and early parachutes were tested at Port-Aviation. Tragic firsts also occurred there: The first death of a pilot in a crash while at the controls of an airplane and the first death of a person on the ground killed by a falling airplane both took place at Port-Aviation.

After Port-Aviation closed, its land became a housing development. The housing district constructed on the site of the former airfield also is called Port-Aviation.

In the early 20th century, when aviation was regarded as a sport for daredevils, aviation pioneers made their early public flights in the Grand Paris (Greater Paris) region from Issy-les-Moulineaux, Vincennes, and the Château de Bagatelle. Spectators observed them both from grandstands and while swarming around the field in a circus atmosphere. In all cases, aviators had to borrow or rent venues designed or intended for other purposes; at Issy-les-Moulineaux and the Château de Bagatelle, the flights took place at racetracks not designed for aviation, and at Issy-les-Moulineaux and Vincennes flights took place on fields the French Army used for maneuvers and had to be scheduled so as not to interfere with military events.

Seeking a better venue to host aviation events in the Grand Paris region, the Société d’Encouragement à l’Aviation (Society for the Encouragement of Aviation) was formed on 30 July 1908 to establish the world's first true airfield, designed specifically for the use of aviators, as well as the world's first aviation school and first aviation competition. The Society formed the Compagnie de l'Aviation (Aviation Company) to operate the airfield and leased cultivated land from two families in the vicinity of the towns of Viry and Châtillon, about 20 kilometres (12.4 mi) south of the center of Paris. Situated on a perfectly flat 100-hectare (247-acre) plain in a low valley and bisected by the Orge, the land was sheltered from the wind by nearby hills along the banks of the Seine.

The Society for the Encouragement of Aviation called upon the French government's chief architect, Guillaume Tronchet, to design and build what became Port-Aviation and organize the facilities necessary for it to function properly as an aerodrome. Tronchet designed Port-Aviation not as a true airport or aerodrome, but rather as a racecourse for airplanes at a time when airplanes generally flew at an altitude of around 10 metres (33 ft) in competitions and only recently had become reliably capable of making turns. Gabriel Voisin, an architect from Juvisy-sur-Orge, drew up and approved the airfield's race courses. Construction began on 15 October 1908.

Port-Aviation had a 4-kilometre (2.5-mile) elliptical track encompassing a 3-kilometre (1.9 mi) circular grass airfield and stands that could seat 7,000 spectators. When the airfield opened, it contained three marked race courses, of 1,000 metres (3,281 ft), 1,500 metres (4,921 ft), and either 1,645.6 metres (5,399 ft) or 1,666.66 metres (5,468 ft), according to different sources. A fourth course of 2,000 metres (6,562 ft) was added in the autumn of 1909. A signals mast — sometimes considered the ancestor of the airport control tower — stood in the center of the airfield. The grounds included an officials' booth at the start line for races, airplane hangars, an airship hangar, 32 repair and construction sheds, an airplane exhibition and sales hall, a central telephone and telegraph office (with a direct line to London, another to Berlin, and ten to Paris), a post office, a two-story press building, an infirmary, a hotel and reception area for distinguished visitors, a restaurant and buffet, bars, tennis courts, a car park, and the Grand Etang (Great Pond), a body of water in the eastern corner of the property that could accommodate seaplanes. Structures throughout the venue were decorated with depictions of eagles, vultures, and other birds and birds of prey. The Orge, a tributary of the Seine, split into two branches at the airfield, one of which ran along Port-Aviation's northwestern perimeter and the other across the northwestern, northern, and northeastern portions of the airfield itself.