Ancient and Roman Times

According to archaeological evidence, Bonn began asa settlement of the local Germanic tribe (the Ubians) about 30 BC. The name "Bonna" is first mentioned by the Roman writer Florus as the place for a military bridge across the Rhine between 13 and 9 BC.  After the failed attempt by the Romans to conquer the land between Rhine and Elbe, Bonn became one of the legionary fortresses ("castra Bonnensia") along thefrontier of the province Germania Inferior, the remainders of which have been found in the north of the modern city.

One well documented event was the maryrdom of two Thebaean legionaries. The Thebaean Legion was an all Christian legion, which refused to worship the emperor as a god. As punishment the Thebaean Legion's commander, Mauritius was executed in St. Moritz as were many other Thebaean legionaries including Cassius and Florentius, Bonn's patron saints, who were martyred at the location of the present-day Münster basilica. A church was founded over their supposed graves, which eventually grew into the Münster (Bonn Minster), the nucleus of the mediaeval town. At first, the Frakish "Bonnburg" inside the former Roman castle and the "villa basilika" around the martyrs' church developed side by side, until the Normans devastated the land in the ninth century and the Bonnburg was abandoned. The "villa Basilika" was fortified and a market town sprung up outside the gates on the river front.

To date, Bonn's Roman fort remains the largest fort of its type known from the ancient world, i.e. a fort built for one full-size Imperial Legion and its auxiliaries. The fort covered an area of approximately 250,000 square meters. Between its walls it contained a dense grid of streets and a multitude of buildings, ranging from spacious headquarters and large officers' houses to barracks, stables and a military jail. Among the legions stationed in Bonn, the "1st", i.e. the Prima Legio Minervia, seems to have served here the longest. Units of the Bonn legion were deployed to theaters of wars ranging from modern-day Algeria to what nowadays is the Russian republic of Chechnya. The chief Roman road linking the provincial capitals of Cologne and Mainz cut right through the fort where it joined the fort's main road (nowadays, Römerstraße). Once past the South Gate, the Cologne-Mainz road continued along what nowadays are streets named Belderberg, Adenauerallee et al. To both sides of the road, the local settlement, Bonna, grew into a sizable Roman town.

In late antiquity, much of the town seems to have been destroyed by marauding invaders. The remaining civilian population then holed up inside the fort along with the remnants of the troops stationed here. During the final decades of imperial rule, the troops were supplied by Germanic chieftains employed by the Roman administration. When the end came, these troops simply shifted their allegiances to the new barbarian rulers. From the fort, the Bonnburg, as well as from a new, medieval settlement to the South centered around what later became the Münster basilica, grew the medieval city of Bonn.

Medieval Bonn

After the Romans left the town had a very tumultuous history. Bonn has been destroyed and pummeled on so many occasions that it nearly became a pastime. Norman invaders were the first to burn the town to the ground in 881 and again in 892.  In 1198 King Philip of Swabia and Duke Heinrich von Brabant layed seige to Bonn.  

Archbishop Konrad von Hochstaden, who quarreled with the patricians of Cologne, the cathedral city, ordered Bonn to build a wall around the entire settled area in 1244 and granted it a town charter. The reasons for fortrification may have been for the Archbishop's protection as he had apparently begun fighting with Cologne's leaders and often resided in Bonn after the dispute. In 1288 under Sigfried II von Westerburg the archbishopric was transferred from Cologne to Bonn, which has since been transfered back to Cologne. In the following three centuries, the archbishop, who was as prince-elector the secular ruler of his territories outside the free imperial city of Cologne, moved his court gradually to Bonn.  From 1597 Bonn was officially capital and residence for the electorate of Cologne.

The Reformation

Two attempts to introduce Luther's reformation under archbishops Hermann von Wied (1515-1547) and Gebhard Truchseß von Walburg (1583) in Bonn failed. As a result of the "Truchseß Wars", for the next two centuries, the prince-archbishops came from the House of Wittelsbach (the ruling dynasty in Bavaria). In 1582 Archbishop Gebhard Truchsess von Waldburg converted to Calvinism and refused to give up his position as elector. In February of 1583 Waldburg married and was in April of the same year excommunicated by Pope Gregory XIII. After the Truschessian War Gebhard fled to Strassbourg, but not before Bonn felt the rapture of Bavarian troops, who blew up the Godesberg (the archbishop's residence) with 1,500 punds of gun powder.

Bonn survived the Thirty Years War intact, but was almost completely destroyed in 1689 during the War of the League of Augsburg. Habsburg's imperial troups defeated the pro-French Egon von Fürstenberg and imposed their candidate for archbishop, Joseph Clemens von Bayern. Josef Clemens started building the great baroque residence, a work that was taken up by his famous successor Clemens August. Under the popular Clemens August, baroque Bonn reached its peak in a time of peace and prosperity. The Electoral Palace and Poppelsdorf Palace were completed and joined by a grand avenue, today's Poppelsdorfer Allee; the Koblenzer Tor and the Hofgarten park were added. Balthasar Neumann, architect of the residence in Würzburg, built the Heilige Stiege (inspired by the Scala Santa in Rome) on the Kreuzberg.  In the market square, a new city hall (todayknown as Altes Rathaus) was erected. A plan to link the residence in Bonn with the Augustusburgpalace in Brühl near Cologne with another long avenue finally overstrained the state's finances and was soon abandoned. With the death of Clemens August came the Wittelsbach era in 1761 to an end.

The last elector, Max Franz von Habsburg, brought the spirit of the Enlightenment to Bonn. He founded the first university and transformed the southern suburb of Godesberg into a fashionable spa town. The young Beethoven gave his first performances in the Redoute, a Godesberg dance and concert hall. With the occupation of the left side of the Rhine by revolutionary armies in 1794 Bonn comes under French rule until 1814. The city lost its fledgling university and all government functions, the church was stripped of its powers and vast property holdings, the monasteries were dissolved, but its citizens gained legal equality and economic freedom through the "Code Napoléon".

To the Modern Era

The Congress of Vienna awarded the (unenthusiastic) Rhineland to Prussia in 1815. The citizens of Bonn were somewhat placated when the Prussian king founded the Rheinische Friedrich-Wilhelms-Universität. The new university soon attracted famous professors like Arndt, Niebuhr, Argelander and Schlegel. Heinrich Heine and Karl Marx were students here. Seven professors from Bonn were sent to the first democratic German parliament at the Paulskirche in Frankfurt during the Revolution of 1848. The Industrialisation passed Bonn by, but the Kulturkampf, the struggle between the (Protestant) Prussian state and the Catholic church vehemently engaged the mostly Catholic citizenry throughout the 19th century. Bonn again became a prosperous city where many rich industrialists took up residence.

From 1904 the city grew by incorporating the surrounding towns and villages. German defeat in World War I and the Treaty of Versailles brought Bonn another period of occupation, first by Anglo-Canadian troups and from 1920 to 1926 by French troups. The era was marked by hyperinflation and political unrest: resistance against the occupation in the Ruhrkampf on the one hand and separatist attempts to unite the occupied Rhineland with France on the other.

Nationalistic tendencies became more pronounced after the occupying forces left and the entry of German troups into the demilitarised Rhineland (1936) in breach of the Versailles Treaty enhanced the standing of the Nazi government. Minorities, especially the Jewish community, and political adversaries are persecuted by the Nazi state in Bonn as in the rest of Germany. In the Reichskristallnacht (1938) the synagogues in Bonn, Poppelsdorf, Beuel, Bad Godesberg and Mehlem were burnt to the ground. In 1942, the over 400 Jewish citizens still remaining in Bonn were deported to the concentration camps, only seven survived. Much of Bonn's inner city was destroyed by aerial bombing during World War II.

Post WWII

At the end of the war in 1945, Bonn became part of the British zone of occupation and in 1946 of the newly created state of North Rhine-Westphalia.  In 1949 became the provisional capital of West Germany. The choice of Bonn was made mainly due to the advocacy of Konrad Adenauer, a former Cologne Mayor and Chancellor of West Germany after World War II, who came from that area, despite the fact that Frankfurt had most of the needed facilities already and using Bonn was estimated to be 95 Mill DM more expensive than using Frankfurt. Because of its relatively small size for a capital city, Bonn was sometimes referred to, jokingly, as the Bundesdorf (Federal Village).

The still intact Pädagogische Hochschule (teachers academy) houses in 1948 the constitutional convention (Parlamentarischer Rat) for the new federal republic that succeeded the three western zones of occupation in 1949. Bonn became provisional capital of West Germany and the former teachers academy the seat of the two houses of the federal parliament (Bundeshaus), not the least due the advocacy of the first Chancellor, Konrad Adenauer, a citizen of Cologne and resident of Rhöndorf, a suburb southeast of Bonn.

After German unification in 1990, parliament decided that Berlin should again be the German capital and seat of government. While the government and parliament moved, as a compromise, some of the ministries largely remained in Bonn, with only the top officials in Berlin. There was no plan to move these departments, and so Bonn remained a second, unofficial capital with the new title "Federal City" (Bundesstadt). Because of the necessary construction work, the move took until 1999 to complete.