Nyhavn, which means New Harbor(or Harbour in the British English spelling), is a canal waterfront and iconic entertainment district where all tourists are attracted to.  
During the 17th century, when the ships were much smaller, this place was a gateway between the sea and the inner city. 
Sailors used to hang out here, and inevitably it also became a red light district and that lasted for almost 300 years.
In the 1960s, the Nyhavn Society established and it did a big revitalization. This place has since been renovated into a charming promenade.
The famous novel and fairy tale writer Hans Christian Andersen had lived in 3 different houses on Nyhavn, #20, 67 and 18, on and off for a total of about 25 years.
The Little Mermaid was written at Nyhaven 67, where he had resided for 17 years, the longest among the three.