Darmstadt is a city in the state of Hesse in Germany, located in the southern part of the Rhine-Main-Area (Frankfurt Metropolitan Region). Darmstadt has around 160,000 inhabitants, making it the fourth largest city in the state of Hesse after Frankfurt am Main, Wiesbaden and Kassel. Other major and local cities in the surrounding area are Frankfurt am Main and Offenbach, Wiesbaden and Mainz, Mannheim and Heidelberg.

Darmstadt holds the official title "City of Science" (German: Wissenschaftsstadt) as it is a major centre of scientific institutions, universities, and high-technology companies. The European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) and the European Space Operations Centre (ESOC) are located in Darmstadt, as well as GSI Centre for Heavy Ion Research, where several chemical elements such as bohrium (1981), meitnerium (1982), hassium (1984), darmstadtium (1994), roentgenium (1994), and copernicium (1996) were discovered. The existence of the following elements were also confirmed at GSI Centre for Heavy Ion Research: nihonium (2012), flerovium (2009), moscovium (2012), livermorium (2010), and tennessine (2012). The Facility for Antiproton and Ion Research (FAIR) is an international accelerator facility under construction. Darmstadt is also the seat of the world's oldest pharmaceutical company, Merck, which is the city's largest employer.

Darmstadt was formerly the capital of a sovereign country, the Grand Duchy of Hesse and its successor, the People's State of Hesse, a federal state of Germany. As the capital of an increasingly prosperous duchy, the city gained some international prominence and remains one of the wealthiest cities in Europe. In the 20th century, industry (especially chemicals), as well as large science and electronics (later information technology) sectors became increasingly important, and are still a major part of the city's economy. It is also home to the football club SV Darmstadt 98. Alexandra Feodorovna (Alix of Hesse), the wife of Nicholas II of Russia, as well as Maria Alexandrovna (Marie of Hesse), the wife of Alexander III of Russia, who were related, were born in this city.

Darmstadt was the capital of an independent country (the Grand Duchy of Hesse) until 1871 and the capital of the German state of Hesse until 1945. It is due to its past as a capital city that it has many architectural testimonies of this period. Many of its major architectural landmarks were created by Georg Moller who was appointed the court master builder of the Grand Duchy of Hesse. Due to the fact that the last ruling Grand Duke of Hesse, Ernst Ludwig was a grandson of Queen Victoria and brother to Empress Alexandra of Russia, the architecture of Darmstadt has been influenced by British and Russian imperial architecture with many examples still existing, such as the Luisenplatz with its grand-ducal column, the old Hessian State Theatre (at Karolinenplatz) and the Russian Chapel by Leon Benois. The Russian church, St. Mary Magdalene Chapel, is named in honor of the patron saint of Tsar Nicholas' mother and was built of Russian stone on Russian soil brought to Darmstadt by train. It was used by the Russian imperial family and court during regular visits to the Tsarina's brother and family in Darmstadt. The grand-ducal palace of Darmstadt is located in the city centre. It was the residence of the counts of Hesse-Darmstadt, later as Grand Dukes of Hesse by the grace of Napoleon. The rulers of Hesse also owned Jagdschloss Kranichstein, a hunting lodge in Kranichstein which is a nowadays used as a five star hotel. The most famous castle in the Darmstadt region is Frankenstein Castle due to claims that the real castle may have had an influence on Mary Shelley's decision to choose the name Frankenstein for her monster-creating scientist. This castle dates back to the 13th century, but it was acquired by the counts of Hesse-Darmstadt in 1662.