Question: Where was Barbarossa Chandelier crowned Holy Roman Emperor?
Context: Frederick I (German: "Friedrich I" , Italian: "Federico I" ; 1122 – 10 June 1190), also known as Frederick Barbarossa (Italian: "Federico Barbarossa" ), was the Holy Roman Emperor from 1155 until his death.  He was elected King of Germany at Frankfurt on 4 March 1152 and crowned in Aachen on 9 March 1152.  He became King of Italy in 1155 and was crowned Roman Emperor by Pope Adrian IV on 18 June 1155.  Two years later, the term "sacrum " ("holy") first appeared in a document in connection with his Empire.  He was later formally crowned King of Burgundy, at Arles on 30 June 1178.  He was named "Barbarossa " by the northern Italian cities which he attempted to rule: Barbarossa means "red beard" in Italian; in German, he was known as "Kaiser Rotbart ", which has the same meaning. The Barbarossa Chandelier (German: "Barbarossaleuchter") was made on the order of Emperor Frederick I, nicknamed Barbarossa, and his wife Beatrice sometime between 1165 and 1170 and was installed under the cupola of the Palatine Chapel in Aachen Cathedral.  The chandelier was a donation in honour of Mary, Mother of God, the patroness of Aachen Cathedral and simultaneously represented a tribute to the builder of the cathedral, Charlemagne. Holy Roman Empress or Empress of the Holy Roman Empire is the title given to the consort (wife) or regent of the Holy Roman Emperor.  The elective dignity of Holy Roman Emperor was restricted to males only, therefore there was never a Holy Roman Empress regnant, though women such as Theophanu or Maria Theresa of Austria, who controlled the power of rule, served as de facto Empresses regnant. The Azelin chandelier (German: "Azelinleuchter" ) is a Romanesque wheel chandelier, made in the 11th century for the Hildesheim Cathedral in Hildesheim, Germany, a UNESCO World Cultural Heritage site since 1985.  It is the oldest of four extant wheel chandeliers from that period, along with the Hezilo chandelier, also in Hildesheim, the Barbarossa chandelier in the Aachen Cathedral, and the Hartwig chandelier in the Abbey of Comburg.  It was believed to be donated by Bishop Azelin, however his predecessor Thietmar is more likely to be the patron.  Therefore, the chandelier is also called the Thietmar chandelier ("Thietmarleuchter"). The monarchs of Prussia were members of the House of Hohenzollern who were the hereditary rulers of the former German state of Prussia from its founding in 1525 as the Duchy of Prussia.  The Duchy had evolved out of the Teutonic Order, a Roman Catholic crusader state and theocracy located along the eastern coast of the Baltic Sea.  The Teutonic Knights were under the leadership of a Grand Master, the last of whom, Albert, converted to Protestantism and secularized the lands, which then became the Duchy of Prussia.  The Duchy was initially a vassal of the Kingdom of Poland, as a result of the terms of the Prussian Homage whereby Albert was granted the Duchy as part of the terms of peace following the Prussian War.  When the main line of Prussian Hohenzollerns died out in 1618, the Duchy passed to a different branch of the family, who also reigned as Electors of Brandenburg in the Holy Roman Empire.  While still nominally two different territories, Prussia under the suzerainty of Poland and Brandenburg under the suzerainty of the Holy Roman Empire, the two states are known together historiographically as Brandenburg-Prussia.  Following the Second Northern War, a series of treaties freed the Duchy of Prussia from any vassalage to any other state, making it a fully sovereign Duchy in its own right.  This complex situation (where the Hohenzollern ruler of the independent Duchy of Prussia was also a subject of the Holy Roman Emperor as Elector of Brandenburg) laid the eventual groundwork for the establishment of the Kingdom of Prussia in 1701.  For diplomatic reasons, the rulers of the state were known as the King in Prussia from 1701 to 1772; largely because they still owed fealty to the Emperor as Electors of Brandenburg, the "King in Prussia" title (as opposed to "King of Prussia") avoided offending the Emperor.  As the Prussian state grew through several wars and diplomatic moves throughout the 18th century, it became apparent that Prussia had become a Great Power that did not need to submit meekly to the Holy Roman Empire.  By 1772, the pretense was dropped, and the style "King of Prussia" was adopted.  Thus it remained until 1871, when in the aftermath of the Franco-Prussian War, the King of Prussia Wilhelm I was crowned German Emperor.  From that point forward, though the Kingdom of Prussia retained its status as a constituent state of the German Empire, all remaining Kings of Prussia also served as German Emperor, and that title took precedence. The Salian dynasty (German: "Salier" ; also known as the Frankish dynasty after the family's origin and position as dukes of Franconia) was a dynasty in the High Middle Ages.  The dynasty provided four German Kings (1024–1125), all of whom went on to be crowned Holy Roman Emperor (1027–1125); as such, the term "Salic dynasty" is also used to refer to the Holy Roman Empire of the time as a separate term. The Hezilo chandelier (German: "Heziloleuchter" ) is an 11th-century Romanesque wheel chandelier.  It is part of the treasures of the Hildesheim Cathedral in Hildesheim, Germany, which has been a UNESCO World Cultural Heritage site since 1985.  The chandelier was most likely commissioned by Bishop Hezilo of Hildesheim, who rebuilt the cathedral after a fire.  He probably also influenced the program of imagery and inscriptions.  It is the largest of four extant wheel chandeliers of the period; the others surviving examples are the Azelin chandelier (also in Hildesheim), the Barbarossa chandelier in the Aachen Cathedral, and the Hartwig chandelier in the Abbey of Comburg. The Concordat of Worms (Latin: "Concordatum Wormatiense" ), sometimes called the Pactum Calixtinum by papal historians, was an agreement between Pope Calixtus II and Holy Roman Emperor Henry V on September 23, 1122, near the city of Worms.  It brought to an end the first phase of the power struggle between the Papacy and the Holy Roman Emperors and has been interpreted as containing within itself the germ of nation-based sovereignty that would one day be confirmed in the Treaty of Westphalia (1648).  In part this was an unforeseen result of strategic maneuvering between the Church and the European sovereigns over political control within their domains.  The King was recognised as having the right to invest bishops with secular authority ("by the lance") in the territories they governed, but not with sacred authority ("by ring and staff").  The result was that bishops owed allegiance in worldly matters both to the pope and to the king, for they were obliged to affirm the right of the sovereign to call upon them for military support, under his oath of fealty.  Previous Holy Roman Emperors had thought it their right, granted by God, to name Church officials within their territories (such as bishops) and to confirm the Papal election (and, at times of extraordinary urgency, actually name popes).  In fact, the Emperors had been heavily relying on bishops for their secular administration, as they were not hereditary or quasi-hereditary nobility with family interests.  A more immediate result of the Investiture struggle identified a proprietary right that adhered to sovereign territory, recognising the right of kings to income from the territory of a vacant diocese and a basis for justifiable taxation.  These rights lay outside feudalism, which defined authority in a hierarchy of personal relations, with only a loose relation to territory.  The pope emerged as a figure above and out of the direct control of the Holy Roman Emperor. Karl Anselm, 4th Prince of Thurn and Taxis, full German name: "Karl Anselm Fürst von Thurn und Taxis" (2 June 1733, Frankfurt am Main, Free Imperial City of Frankfurt, Holy Roman Empire – 13 November 1805, Winzer bei Regensburg, Electorate of Bavaria, Holy Roman Empire) was the fourth Prince of Thurn and Taxis, Postmaster General of the Imperial Reichspost, and Head of the Princely House of Thurn and Taxis from 17 March 1773 until his death on 13 November 1805.  Karl Anselm served as "Prinzipalkommissar" at the Perpetual Imperial Diet in Regensburg for Joseph II, Holy Roman Emperor and Francis II, Holy Roman Emperor from 1773 to 1797. Beatrice of Burgundy (1143 – 15 November 1184) was a Sovereign Countess of Burgundy from 1148 until her death, and a Holy Roman Empress by marriage to Frederick I, Holy Roman Emperor.  She was crowned Holy Roman Empress by Antipope Paschal III in Rome on 1 August 1167, and as Queen of Burgundy at Vienne in August 1178.
Answer: Aachen