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.

Oggenhausen and Großkuchen became part of Heidenheim during the last district reform in the 1970s and are also municipalities under state administrative law.

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.

Although largely residential, Schnaitheim is home to a number of Heidenheim's "Big Box"-style retailers, and its commercial districts are an important part of the city's infrastructure.

Other neighbourhoods include Hagen on the west side, located on the slope of a hill and Aufhausen, once a separate farming village to the north but now amalgamated.

About 5 kilometers to the east of Heidenheim, separated by the major road European route E43, the village of Oggenhausen is home to about 1550 residents.

About 8 kilometres north-east of Heidenheim, the geographically separate Großkuchen is a popular recreational area with hiking trails and cross-country skiing.

There is evidence that human life existed within the city limits of Heidenheim as far back as 8,000 years ago.

At the time of the Roman Empire from about 85 AD onwards, Heidenheim was the location of Castle Aquileia with attached cavalry of more than 1,000 mounted soldiers.

The unit, called ala II flavia milliaria was later, around 159 AD, moved further North to Aalen.

But it did not take long until a civilian settlement was founded at this strategically important spot, marked by the intersection of five Roman roads.

This settlement was the largest Roman city in what is today Baden-Württemberg and archeological finds suggest that it covered an area of approximately 37 - 50 acres (20.23 ha) (15 - 20 hectares).

Its exact function was not fully understood as of May 2005, but given Aquileia's size, location and other indicators, it is believed that it was probably the capital of a Roman administrative district (see also Civitas).

The economic development of the village and city is founded mainly on the area's ore deposits that were already being exploited in Roman times.

However, the importance of this branch of the city's economy diminished near the turn of the 19th century due to great competition, first from Wasseralfingen and later from the Rhineland.

The business grew into an industry at the dawn of the 19th century with the help of cotton imports but declined after World War II due to international competition.

Mergelstetten was first mentioned in an official document by Bishop Walter von Augsburg in 1143 in which he confirmed that the nearby Cloister of Anhausen owned a mill, a fish pond and a farm.

Großkuchen remained Catholic because ecumenically it belonged to Öttingen and because the Benedictine Abbey at Neresheim owned the right to use the village church.

All Protestant parishes within city limits belong to the Deanony of Heidenheim within the Evangelical-Lutheran Church in Württemberg.

Catholics from Oggenhausen belong to the Holy Heart of Jesus parish in Nattheim (Ministry 1), also part of the Deacony of Heidenheim.

Figures reflect city limits at the time and are estimates or Census data (1), or official extensions thereof, counting only primary residences.

Since the last municipal elections in 2019, the city council of Heidenheim has consisted of 33 (previously 34) members, each serving a term of five years.

Mayors of Heidenheim an der Brenz since 1819 The coat of arms of the city of Heidenheim an der Brenz features a bearded "heathen" wearing a red cap with a blue rim and a red shirt with a blue collar on golden background.

Notable structures in the inner city are the Protestant Michaels' Church (the former parish seat of the city), the Elmar-Doch-House, the Crown Inn and Pub, the Lower Gate, Villa Waldemaier, the burgher tower Türmle, the Castle Pharmacy, the weavers' settlement, the Heathland smithy, the Old mint and the old Peters' Church (today cemetery chapel).

The construction facility for the manufacture of large turbines built for the local Voith company in 1924 is a significant industrial historic landmark.

The little castle in Schnaitheim is situated at the Brenz river's edge and offers a sight to see for visitors and residents alike.

Every other year the Shepherd Run takes place in Heidenheim, first held in 1723 by Duke Eberhard Ludwig.

In recent years it has received international recognition and critical acclaim under the artistic direction of conductor Marco-Maria Canonica.

The Opernfestspiele Heidenheim draws visitors from around Europe and overseas, and has significantly boosted the city's reputation as an important cultural site.

The team has experienced success in recent years, rising two tiers in the German football league system after winning the Regionalliga Süd in 2009.