Imperial Cathedral in its original context means a cathedral

Cathedral

A cathedral is a Christian church that contains the seat of a bishop...

 linked to the german emperor

Emperor

An emperor is a monarch, usually the sovereign ruler of an empire or another type of imperial realm. Empress, the female equivalent, may indicate an emperor's wife or a woman who rules in her own right...

s.

The Romanesque

Romanesque architecture

Romanesque architecture is an architectural style of Medieval Europe characterised by semi-circular arches. There is no consensus for the beginning date of the Romanesque architecture, with proposals ranging from the 6th to the 10th century. It developed in the 12th century into the Gothic style,...

 cathedrals on the Rhine in Mainz

Mainz

Mainz under the Holy Roman Empire, and previously was a Roman fort city which commanded the west bank of the Rhine and formed part of the northernmost frontier of the Roman Empire...

, Worms

Worms, Germany

Worms is a city in Rhineland-Palatinate, Germany, on the Rhine River. At the end of 2004, it had 85,829 inhabitants.Established by the Celts, who called it Borbetomagus, Worms today remains embattled with the cities Trier and Cologne over the title of "Oldest City in Germany." Worms is the only...

 and Speyer

Speyer

Speyer is a city of Rhineland-Palatinate, Germany with approximately 50,000 inhabitants. Located beside the river Rhine, Speyer is 25 km south of Ludwigshafen and Mannheim. Founded by the Romans, it is one of Germany's oldest cities...

 are called Imperial Cathedrals.

Mainz Cathedral

Mainz Cathedral

Mainz Cathedral or St. Martin's Cathedral is located near the historical center and pedestrianized market square of the city of Mainz, Germany...

 was built by archbishop

Archbishop

An archbishop is a bishop of higher rank, but not of higher sacramental order above that of the three orders of deacon, priest , and bishop...

 Willigis of Mainz, then regent

Regent

A regent, from the Latin regens "one who reigns", is a person selected to act as head of state because the ruler is a minor, not present, or debilitated. Currently there are only two ruling Regencies in the world, sovereign Liechtenstein and the Malaysian constitutive state of Terengganu...

 of the empire, in the years after 975. Henry IV

Henry IV, Holy Roman Emperor

Henry IV was King of the Romans from 1056 and Holy Roman Emperor from 1084 until his forced abdication in 1105. He was the third emperor of the Salian dynasty and one of the most powerful and important figures of the 11th century...

 also contributed to the building after 1081. Mainz Cathedral was coronation site for Philipp von Schwaben, Frederick II

Frederick II, Holy Roman Emperor

Frederick II , was one of the most powerful Holy Roman Emperors of the Middle Ages and head of the House of Hohenstaufen. His political and cultural ambitions, based in Sicily and stretching through Italy to Germany, and even to Jerusalem, were enormous...

, and Henry Raspe. Also Henry II

Henry II, Holy Roman Emperor

Henry II , also referred to as Saint Henry, Obl.S.B., was the fifth and last Holy Roman Emperor of the Ottonian dynasty, from his coronation in Rome in 1014 until his death a decade later. He was crowned King of the Germans in 1002 and King of Italy in 1004...

 (in 1002), and Conrad II

Conrad II, Holy Roman Emperor

Conrad II was Holy Roman Emperor from 1027 until his death.The son of a mid-level nobleman in Franconia, Count Henry of Speyer and Adelaide of Alsace, he inherited the titles of count of Speyer and of Worms as an infant when Henry died at age twenty...

 (in 1024) were crowned in the cathedral at Mainz, but both presumably in the preceding building, since the present cathedral was consecrated in 1038 after their coronations.

Speyer Cathedral

Speyer Cathedral

The Speyer Cathedral, officially the Imperial Cathedral Basilica of the Assumption and St Stephen, in Latin: Domus sanctae Mariae Spirae in Speyer, Germany, is the seat of the Roman Catholic Bishop of Speyer and is suffragan to the Archdiocese of Bamberg. The cathedral, which is dedicated to St...

 was built starting in 1030 by Conrad II

Conrad II, Holy Roman Emperor

Conrad II was Holy Roman Emperor from 1027 until his death.The son of a mid-level nobleman in Franconia, Count Henry of Speyer and Adelaide of Alsace, he inherited the titles of count of Speyer and of Worms as an infant when Henry died at age twenty...

 as a family vault for the Salian dynasty

Salian dynasty

The Salian dynasty was a dynasty in the High Middle Ages of four German Kings , also known as the Frankish dynasty after the family's origin and role as dukes of Franconia...

 and was later extended by Henry IV

Henry IV, Holy Roman Emperor

Henry IV was King of the Romans from 1056 and Holy Roman Emperor from 1084 until his forced abdication in 1105. He was the third emperor of the Salian dynasty and one of the most powerful and important figures of the 11th century...

.

Worms Cathedral

Worms Cathedral

Cathedral of St Peter is a church in Worms, southern Germany. It was the seat of the Catholic Prince-Bishopric of Worms until its extinction in 1800.It is a basilica with four round towers, two large domes, and a choir at each end...

 houses the tombs of emperor Conrad's II

Conrad II, Holy Roman Emperor

Conrad II was Holy Roman Emperor from 1027 until his death.The son of a mid-level nobleman in Franconia, Count Henry of Speyer and Adelaide of Alsace, he inherited the titles of count of Speyer and of Worms as an infant when Henry died at age twenty...

 family and also got its status because of its size and glory.
Less well known is that the Salian built basilica in Koenigslutter, under the reign of Lothair III

Lothair III, Holy Roman Emperor

Lothair III of Supplinburg , was Duke of Saxony , King of Germany , and Holy Roman Emperor from 1133 to 1137. The son of Count Gebhard of Supplinburg, his reign was troubled by the constant intriguing of Frederick I, Duke of Swabia and Duke Conrad of Franconia...

, also is traditionally called Imperial Cathedral. The Cathedral in Bamberg

Bamberg Cathedral

The Bamberg Cathedral is a church in Bamberg, Germany, completed in the 13th century. The cathedral is under the administration of the Roman Catholic Church and is the seat of the Archbishop of Bamberg....

, built under reign of Henry II

Henry II, Holy Roman Emperor

Henry II , also referred to as Saint Henry, Obl.S.B., was the fifth and last Holy Roman Emperor of the Ottonian dynasty, from his coronation in Rome in 1014 until his death a decade later. He was crowned King of the Germans in 1002 and King of Italy in 1004...

, where the only canonized

Canonization

Canonization is the act by which a Christian church declares a deceased person to be a saint, upon which declaration the person is included in the canon, or list, of recognized saints. Originally, individuals were recognized as saints without any formal process...

 married couple has their grave, also has the same status. Aachen Cathedral

Aachen Cathedral

Aachen Cathedral, frequently referred to as the "Imperial Cathedral" , is a Roman Catholic church in Aachen, Germany. The church is the oldest cathedral in northern Europe and was known as the "Royal Church of St. Mary at Aachen" during the Middle Ages...

 and the Frankfurt Cathedral

Frankfurt Cathedral

Saint Bartholomeus's Cathedral is a Gothic building located in Frankfurt, Germany.Frankfurt Cathedral is the main church of Frankfurt and was constructed in the 14th and 15th centuries on the foundation of an earlier church from the Merovingian time...

(Cathedral of Saint Bartholomew) in Frankfurt were also described as imperial cathedrals because they were the coronation

Coronation

A coronation is a ceremony marking the formal investiture of a monarch and/or their consort with regal power, usually involving the placement of a crown upon their head and the presentation of other items of regalia...

cathedrals of emperors and kings.