Early history and Holy Roman Empire

At the western borders of Frankfurt lies the Kapellenberg as part of the Taunus with one of the first Stone Age cities in Europe.[1] The Celts had different settlements in the Taunus mountains north of Frankfurt, the biggest one the Heidetrank Oppidum. The first traces of Roman settlements established in the area of the river Nidda date to the reign of Emperor Vespasian in the years 69 to 79 AD. Nida (modern Heddernheim, Praunheim) was a Roman civitas capital (Civitas Taunensium).

Alemanni and Franks lived there, and by 794, Charlemagne presided over an imperial assembly and church synod, at which Franconofurd (alternative spellings end with -furt and -vurd) was first mentioned. It was one of the two capitals of Charlemagne's grandson Louis the German, together with Regensburg. Louis founded the collegiate church, rededicated in 1239 to Bartholomew the Apostle and now Frankfurt Cathedral.[2]

Frankfurt was one of the most important cities in the Holy Roman Empire. From 855, the German kings were elected and crowned in Aachen. From 1562, the kings and emperors were crowned and elected in Frankfurt, initiated for Maximilian II. This tradition ended in 1792, when Francis II was elected. His coronation was deliberately held on Bastille Day, 14 July, the anniversary of the storming of the Bastille. The elections and coronations took place in St. Bartholomäus Cathedral, known as the Kaiserdom (Emperor's Cathedral), or its predecessors.

The Frankfurter Messe ('Frankfurt Trade Fair') was first mentioned in 1150. In 1240, Emperor Frederick II granted an imperial privilege to its visitors, meaning they would be protected by the empire. The fair became particularly important when similar fairs in French Beaucaire lost attraction around 1380. Book trade fairs began in 1478.

In 1372, Frankfurt became a Reichsstadt (Imperial Free City), i.e., directly subordinate to the Holy Roman Emperor and not to a regional ruler or a local nobleman.

In 1585, Frankfurt traders established a system of exchange rates for the various currencies that were circulating to prevent cheating and extortion. Therein lay the early roots for the Frankfurt Stock Exchange.

Frankfurt managed to remain neutral during the Thirty Years' War, but suffered from the bubonic plague that refugees brought to the city. After the war, Frankfurt regained its wealth. In the late 1770s the theater principal Abel Seyler was based in Frankfurt, and established the city's theatrical life.[3]

Impact of French revolution and the Napoleonic Wars

Following the French Revolution, Frankfurt was occupied or bombarded several times by French troops. It remained a Free city until the collapse of the Holy Roman Empire in 1805/6. In 1806, it became part of the principality of Aschaffenburg under the Fürstprimas (Prince-Primate), Karl Theodor Anton Maria von Dalberg. This meant that Frankfurt was incorporated into the Confederation of the Rhine. In 1810, Dalberg adopted the title of a Grand Duke of Frankfurt. Napoleon intended to make his adopted son Eugène de Beauharnais, already Prince de Venise ("prince of Venice", a newly established primogeniture in Italy), Grand Duke of Frankfurt after Dalberg's death (since the latter as a Catholic bishop had no legitimate heirs). The Grand Duchy remained a short episode lasting from 1810 to 1813 when the military tide turned in favor of the Anglo-Prussian-led allies that overturned the Napoleonic order. Dalberg abdicated in favor of Eugène de Beauharnais, which of course was only a symbolic action, as the latter effectively never ruled after the ruin of the French armies and Frankfurt's takeover by the allies.

Frankfurt as a fully sovereign state

After Napoleon's final defeat and abdication, the Congress of Vienna (1814–1815) dissolved the grand-duchy and Frankfurt became a fully sovereign city-state with a republican form of government. Frankfurt entered the newly founded German Confederation (till 1866) as a free city, becoming the seat of its Bundestag, the confederal parliament where the nominally presiding Habsburg Emperor of Austria was represented by an Austrian "presidential envoy".

After the ill-fated revolution of 1848, Frankfurt was the seat of the first democratically elected German parliament, the Frankfurt Parliament, which met in the Frankfurter Paulskirche (St. Paul's Church) and was opened on 18 May 1848. In the year of its existence, the assembly developed a common constitution for a unified Germany, with the Prussian king as its monarch. The institution failed in 1849 when the Prussian king, Frederick William IV, declared that he would not accept "a crown from the gutter".

Frankfurt after the loss of sovereignty  View of Frankfurt am Main, including the Alte Brücke (Old Bridge), by Gustave Courbet (1858)

Frankfurt lost its independence after the Austro-Prussian War in 1866 when Prussia annexed several smaller states, among them the Free City of Frankfurt. The Prussian administration incorporated Frankfurt into its province of Hesse-Nassau. The Prussian occupation and annexation were perceived as a great injustice in Frankfurt, which retained its distinct western European, urban and cosmopolitan character. The formerly independent towns of Bornheim and Bockenheim were incorporated in 1890.

In 1914, the citizens founded the University of Frankfurt, later named Goethe University Frankfurt. This marked the only civic foundation of a university in Germany; today it is one of Germany's largest.

From 6 April to 17 May 1920, following military intervention to put down the Ruhr uprising, Frankfurt was occupied by French troops.[4] The French claimed that Articles 42 to 44 of the peace treaty of Versailles concerning the demilitarization of the Rhineland had been broken.[5] In 1924, Ludwig Landmann became the first Jewish mayor of the city, and led a significant expansion during the following years. During the Nazi era, the synagogues of the city were destroyed and the vast majority of the Jewish population fled or was killed.[6]

During World War II, Frankfurt was the location of a Nazi prison for underage girls with several forced labour camps,[7] a camp for Sinti and Romani people (see Romani Holocaust),[8] the Dulag Luft West transit camp for Allied prisoners of war,[9] and a subcamp of the Natzweiler-Struthof concentration camp.[10]

Frankfurt was severely bombed in World War II (1939–1945). About 5,500 residents were killed during the raids, and the once-famous medieval city center, by that time the largest in Germany, was almost completely destroyed. It became a ground battlefield on 26 March 1945, when the Allied advance into Germany was forced to take the city in contested urban combat that included a river assault. The 5th Infantry Division and the 6th Armored Division of the United States Army captured Frankfurt after several days of intense fighting, and it was declared largely secure on 29 March 1945.[11]

After the end of the war, Frankfurt became a part of the newly founded state of Hesse, consisting of the old Hesse-(Darmstadt) and the Prussian Hesse provinces. The city was part of the American Zone of Occupation of Germany. The Military Governor for the United States Zone (1945–1949) and the United States High Commissioner for Germany (HICOG) (1949–1952) had their headquarters in the IG Farben Building, intentionally left undamaged by the Allies' wartime bombardment.

Frankfurt was the original choice for the provisional capital city of the newly founded state of West Germany in 1949. The city constructed a parliament building that was never used for its intended purpose (it housed the radio studios of Hessischer Rundfunk). In the end, Konrad Adenauer, the first postwar Chancellor, preferred the town of Bonn, for the most part because it was close to his hometown, but also because many other prominent politicians opposed the choice of Frankfurt out of concern that Frankfurt would be accepted as the permanent capital, thereby weakening the West German population's support for a reunification with East Germany and the eventual return of the capital to Berlin.

Postwar reconstruction took place in a sometimes simple modern style, thus changing Frankfurt's architectural face. A few landmark buildings were reconstructed historically, albeit in a simplified manner (e.g., Römer, St. Paul's Church, and Goethe House). The collection of historically significant Cairo Genizah documents of the Municipal Library was destroyed by the bombing. According to Arabist and Genizah scholar S.D. Goitein, "not even handlists indicating its contents have survived."[12]

The end of the war marked Frankfurt's comeback as Germany's leading financial hub, mainly because Berlin, now a city divided into four sectors, could no longer rival it. In 1948, the Allies founded the Bank deutscher Länder, the forerunner of Deutsche Bundesbank. Following this decision, more financial institutions were re-established, e.g. Deutsche Bank and Dresdner Bank. In the 1950s, Frankfurt Stock Exchange regained its position as the country's leading stock exchange.

Frankfurt also reemerged as Germany's transportation hub and Frankfurt Airport became Europe's second-busiest airport behind London Heathrow Airport in 1961.

During the 1970s, the city created one of Europe's most efficient underground transportation systems.[13] That system includes a suburban rail system (S-Bahn) linking outlying communities with the city center, and a deep underground light rail system with smaller coaches (U-Bahn) also capable of travelling above ground on rails.

In 1998, the European Central Bank was founded in Frankfurt, followed by the European Insurance and Occupational Pensions Authority and European Systemic Risk Board in 2011.