Altenheim is located some 10 km east by south-east of Saverne and 30 km north-west of Strasbourg. It can be accessed from five directions: from Furchhausen in the west by road D230, from Dettwiller in the north by road D112, from Littenheim in the east by road D151, from Saessolsheim in the south-east by road D230, and from Wolschheim in the south by road D112. All these roads intersect in the village. The commune consists entirely of farmland other than the village. The only waterway in the commune is the Drusenbach crossing the south-western corner and two small tributaries of this stream in the north of the commune.
On 21 January 1945, an American B-17 bomber,the "Princess Pat" was hit by flak returning from a mission to Heilbronn and landed on its belly near the D230 road between Altenheim and Furchhausen.
In 2009, the commune had 226 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][Note 2]
^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 in 1 January 2009 and was based on the census of 2006.
^In the census table and the graph, by convention in Wikipedia, and to allow a fair comparison between five yearly censuses, the principle has been retained for subsequent legal populations since 1999 displayed in the census table and the graph that shows populations for the years 2006, 2011, 2016, etc.. , as well as the latest legal population published by INSEE