Heidelberg, formally known as Heidelberg am Neckar, is a city in the northwest of Baden-Württemberg, Germany with approximately 160,000 inhabitants (2019).
The city is situated on the Neckar River about 20 km (12 mi) south of Mannheim, and about 100 km (60 mi) south of Frankfurt am Main.
Heidelberg is well-known for its preserved Old Town, its red sandstone castle and as a university town.