|Location (in red) within Paris inner and outer suburbs|
|Elevation||138 m (453 ft) avg.|
|Land area1||13.0 km2 (5.0 sq mi)|
|- Density||2,205 /km2 (5,710 /sq mi)|
|INSEE/Postal code||78297/ 78280|
|1 French Land Register data, which excludes lakes, ponds, glaciers > 1 km² (0.386 sq mi or 247 acres) and river estuaries.|
|2 Population without double counting: residents of multiple communes (e.g., students and military personnel) only counted once.|
Guyancourt (pronounced: [ɡɥi.jɑ̃.kuʁ]) is a commune in the Yvelines department in the Île-de-France region in north-central France. It is located in the south-western suburbs of Paris 21.2 km (13.2 mi) from the center, in the "new town" of Saint-Quentin-en-Yvelines.
The commune of Guyancourt comprises several districts. The first of them, corresponding to the old village, is known as "le village", the others are named:
- Bouviers (Herdsmen), ancient hamlet of the village
- Les Garennes (the warrens)
- L'Europe (Europe)
- Le Pont du Routoir (the bridge over the retting pit)
- Les Saules (the Willows)
- Le Parc (the Park)
- Les Chênes (the Oaks)
- Villaroy (the recently constructed districts of the city)
Although located in the Paris suburbs (in an Anglo-Saxon conception of suburbs), more than half of the territory of the commune of Guyancourt is covered in natural spaces: forests, wood, parks, gardens and ponds.
The site of the city was already inhabited by Neolithic tribes who left hundreds of vestiges such as arrows, flint scrapers, polished axes... which have been recovered in the districts of Bouviers, Troux and Villaroy.
The civilization continued through Roman times, as Mr. Leclère, a farmer, demonstrated in a fortuitous way in 1892 by unearthing an antique ballot box in his field.
The religious life 
Work to restore the church Saint-Victor put the date of the sarcophages at the Merovingian era (from the seventh century). It is believed that the construction of the first church dates from the fourteenth century. Several funerary vases and a tomb stone dating from the sixteenth century were updated. The church was renovated in the fifteenth century, then entirely rebuilt in the sixteenth century. The most recent restoration goes back to 1998.
Guyancourt and the Palace of Versailles 
Guyancourt forms part of the "Grand Parc" of the sun king Soleil (Louis XIV), which extended around the castle of Versailles. The essential vocation of the populous communes neighbouring the castle is market-gardening, to provide for the important needs for the Court.
French revolution 
Thanks to the register of grievances sent to the governmental authorities (1789), we know that Guyancourtois, who were mostly modest peasants, lived with difficulty under conditions of famine.
The Franco-Prussian War of 1870 
France is partly occupied by the Prussian armies. The enemy spreads terror, the houses are plundered, the inhabitants maltreated. Four hundred of them (an enormous figure for the time) prefer to flee.
The 1900s 
At the beginning of the twentieth century, Guyancourt was a large village where one cultivates corn, oats, beets, fodder and potatoes. The trades were numerous, with almost 16 wine merchants for 614 inhabitants.
First World War 
The war of 1914–1918 cost the lives of thirty-six Guyancourtois.
Second World war 
The war of 1939–1945 also touched Guyancourt, which was liberated by August 25, 1944.
The end of the twentieth century 
Starting from the beginning of the 1950s, the Paris area saw a considerable demographic growth. To structure the development of the suburbs, it was decided to create several new towns around Paris, one of which being Saint-Quentin-en-Yvelines. The new city of Saint-Quentin-en-Yvelines includes today seven communes (eleven in the beginning), one of which is Guyancourt. In 1950 Guyancourt was only one small village. The commune grew since 1970 to reach the figure of 27,000 inhabitants in 2004.
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International relations 
Twin towns — Sister cities 
Guyancourt is twinned with:
- Roland Nadaus: Poet, writer, lampoonist, storyteller, lyric writer, novelist, local councillor and départemental. The author of about thirty works, he also assumed several mandates of mayor, advising general, and President of the urban community (then called the SAN, trade union of new agglomeration).
Industrial fabric 
Guyancourt accommodates not only many SME and trade, but also several large companies, such as:
- Le Technocentre Renault (automobile)
- The head office of Bouygues Construction
- The national case of Crédit Agricole
- The registered office of McDonald's, France
- Prost Grand Prix (closed now).
Higher education and research 
- Guyancourt is home to a campus of the University of Versailles-Saint-Quentin. The buildings located in the commune relate to the lessons on human rights and the social sciences.
- One also finds there research laboratories of the INRA (National Institute of Agronomic Research)
Guyancourt is served by no station of the Paris Métro, RER, or suburban rail network. The closest station to Guyancourt is Saint-Quentin-en-Yvelines station on Paris RER line C, on the Transilien La Défense suburban rail line, and on the Transilien Paris – Montparnasse suburban rail line. This station is located in the neighboring commune of Montigny-le-Bretonneux, 2.7 km (1.7 mi) from the town center of Guyancourt.
See also 
- Ville of Guyancourt, official site
- Site of the district of Villaroy
- Site of the district of the Willows
- new City of Saint-Quentin-in-Yvelines