The Imperial Crown , is the hoop crown

Hoop crown

A hoop crown is a crown consisting of a "band around the temples and one or two bands over the head". First used by the Carolingian dynasty, hoop crowns became increasingly popular among royal dynasties in the Late Middle Ages, and the dominant type of crown in the Modern Era.-Origins:Hoop crowns...

  of the King of the Romans

King of the Romans

King of the Romans was the title used by the ruler of the Holy Roman Empire following his election to the office by the princes of the Kingdom of Germany...

, the rulers of the German Kingdom, since the High Middle Ages

High Middle Ages

The High Middle Ages was the period of European history around the 11th, 12th, and 13th centuries . The High Middle Ages were preceded by the Early Middle Ages and followed by the Late Middle Ages, which by convention end around 1500....

. Most of the kings were crowned with it. It was made probably somewhere in Western Germany, either under Otto I

Otto I, Holy Roman Emperor

Otto I the Great , son of Henry I the Fowler and Matilda of Ringelheim, was Duke of Saxony, King of Germany, King of Italy, and "the first of the Germans to be called the emperor of Italy" according to Arnulf of Milan...

 (with additions 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...

), 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...

 or Conrad III

Conrad III of Germany

Conrad III was the first King of Germany of the Hohenstaufen dynasty. He was the son of Frederick I, Duke of Swabia, and Agnes, a daughter of the Salian Emperor Henry IV.-Life and reign:...

 during the late 10th and early 11th centuries. The first preserved mention of it is from the 12th century — assuming it is the same crown, which seems very probable.

Along with the Imperial Cross

Cross of Lothair

The Cross of Lothair or Lothair Cross is a crux gemmata processional cross dating from about 1000 AD, though its base dates from the 14th century. It was made in Germany, probably at Cologne...

 (Reichskreuz), the Imperial Sword

Imperial Sword

The Imperial Sword , is one of four Imperial Regalia of the Holy Roman Empire. During the coronation, it was given to the emperor along with the sceptre and the Imperial Orb...

 (Reichsschwert), and the Holy Lance (Heilige Lanze), the crown was the most important part of the Imperial Regalia

Imperial Regalia

The Imperial Regalia, insignia, or crown jewels are the regalia of the Emperors and Kings of the Holy Roman Empire. The most important parts are the Imperial Crown, the Holy Lance and the Imperial Sword...

 (Reichskleinodien).