The name Helsingør is derived from the word hals meaning "neck" or "narrow strait", referring to the narrow strait (Øresund Øre Sound or, locally Sundet "The Sound" ) between what is now Helsingør and Helsingborg, Sweden. The Rerum Danicarum Historica (1631) claims that the history of Helsingør can be traced back to 70 BC, but this information is highly dubious. The people were mentioned as Helsinger (which may mean "the people of the strait") for the first time in King Valdemar the Victorious's Liber Census Daniæ from 1231, but they should not be confused with the Helsings of Hälsingland in Sweden. Placenames show that the Helsinger may have had their main fort at Helsingborg and a fortified landing place at Helsingør, to control the ferry route across the strait.
Before the Middle Ages, Helsingør was just a marketplace where people sold goods. About 1200 AD, the first church, Sct Olav Church, was built. A number of convents once surrounded the church, but now all that remains is the church building, today the cathedral of the Diocese of Helsingør. The oldest parts of the cathedral of Helsingør date back to the 13th century and tell us that the fishermen's village, as Helsingør was then, was a town of a certain importance. At least, there has always been some form of ferryboat crossing between Helsingør and Helsingborg.
Helsingør, as it is known today, was founded in the 1420s by the Danish king Eric of Pomerania. He established the Sound Dues in 1429 and built the castle Krogen, which was expanded in the 1580s and named Kronborg.
Kronborg Castle is the main tourist attraction. The play Hamlet has been performed a number of times in its courtyard.
The Swedish city of Helsingborg lies a short distance across the Øresund from Helsingør. European route E55 joins the two cities; ferries connect the two sides