Nidaros was the old name of Trondheim (Trond(h)jem, sometimes Drontheim), a city of Norway, in the Middle Ages. Nidaros was Northern Europe's most important Christian pilgrimage site during this time, the pilgrims' goal being the Christ Church, also known as the Nidaros Cathedral, established as the seat of the archdiocese of all Norway in 1152 by Nicholas Breakspeare, who later became the only English pope as Adrian IV. The archdiocese thus broke away from the newly established archbishopric of Scandinavia, situated in Lund, Skåne (then a part of the Danish realm) since 1103. Nidaros town owed its name to the location at the mouth of the river Nid (Nidelva) (os = river mouth).
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Noun 1. a port in central Norway on Trondheim Fjord (synonym) Trondheim (hypernym) city, metropolis, urban center (part-holonym) Norway, Kingdom of Norway, Norge, Noreg