Armentières-sur-Ourcq is located some 30 km south of Soissons and 30 km south-east of Villers-Cotterêts. The D1 road runs through the south-west corner of the commune however the main access is on the D79 from La Croix-sur-Ourcq in the south-west running to the village then west to Nanteuil-Notre-Dame in the east. The D80 road also comes from Oulchy-le-Château in the north and continues south to Coincy. The commune is almost entirely farmland except for a belt of forest in the north.
The Ourcq river flows from east to west through the northern part of the commune and forming part of the northern border. The Ru Garnier stream flows from the south of the commune north through the village and continuing north to join the Ourcq river.
In 2010 the commune had 98 inhabitants. The evolution of the number of inhabitants is known through the population censuses conducted in the town since 1793. From the 21st century, a census of municipalities with fewer than 10,000 inhabitants is held every five years, unlike larger towns that have a sample survey every year.[Note 1]
The commune has two sites that are registered as historical monuments:
The Chateau of Armentières (12th century). Its postern has been classified as a historical monument since 25 January 1921. It is currently privately owned and is visited every year during European Heritage Days. Since 2004 it has benefited from restoration works supported by the DRAC of Picardy and the General Council of Aisne
The Bernard bridges (17th century) spanning the Ourcq.
Other sites of interest
The Church (13th century) was severely damaged during the First World War and almost entirely rebuilt. It contains two items that are registered as historical objects:
A Bas-relief: Pietà Donatrice and patron (16th century)
A Funeral Monument of the Lords of Armentières (16th century)
^At the beginning of the 21st century, the methods of identification have been modified by law No. 2002-276 of 27 February 2002 , the so-called "law of local democracy" and in particular Title V "census operations" which allow, after a transitional period running from 2004 to 2008, the annual publication of the legal population of the different French administrative districts. For municipalities with a population greater than 10,000 inhabitants, a sample survey is conducted annually, the entire territory of these municipalities is taken into account at the end of the period of five years. The first "legal population" after 1999 under this new law came into force on 1 January 2009 and was based on the census of 2006.