Heidenheim an der Brenz, or just Heidenheim (; Swabian: Hoidna or Hoirna), is a town in Baden-Württemberg in southern Germany. It is located near the border with Bavaria, approximately 17 km south of Aalen and 33 km north of Ulm. Heidenheim is the largest town and the seat of the district of Heidenheim, and ranks third behind Aalen and Schwäbisch Gmünd in size among the towns in the region of East Württemberg. Heidenheim is the economic center for all the communities in Heidenheim district and is the headquarters of the Voith industrial company. The town's population passed the 20,000 mark in 1925. Heidenheim collaborates with the town of Nattheim in administrative matters. The residents of Heidenheim and its surrounding area speak the distinct German dialect of Swabian. Geography Heidenheim is situated between Albuch and the Härtsfeld region in the northeast corner of the Swabian Alb where the valley of the Brenz meets the Stubental at the foot of Hellenstein Mountain. The source of the Brenz is located in Königsbronn and enters Heidenheim from the northwest. It runs through the boroughs of Aufhausen and Schnaitheim before it gets to Heidenheim (proper). From there it continues on to the south through the borough of Mergelstetten, before it leaves the city limits to head for Herbrechtingen. Neighbouring municipalities Heidenheim shares borders with the following cities and towns, listed clockwise starting from the North: Aalen and Neresheim (both in Ostalb County), Nattheim (Heidenheim County), Syrgenstein (Dillingen County, Bavaria), as well as Herbrechtingen, Steinheim am Albuch and Königsbronn (all in Heidenheim County). Subdivisions Heidenheim an der Brenz consists of Heidenheim (proper) and the subdivisions (boroughs) of Schnaitheim, Mergelstetten, Oggenhausen and Großkuchen (annexed between 1910 and 1974). Each of the four boroughs includes their own neighbourhoods that either have a long history of their own or were created as new developments. But while these neighbourhoods received their names during construction, their boundaries have not been officially defined. Oggenhausen and Großkuchen became part of Heidenheim during the last district reform in the 1970s and are also municipalities under state administrative law. This designation entitles them to a borough council, elected by registered voters in municipal elections. The Municipal Council is headed by a president. Schnaitheim Schnaitheim, to the north, was at one time a politically independent small town but is now Heidenheim's largest borough, officially known as Heidenheim-Schnaitheim. Expansion of both towns has now eradicated any geographical