[1][2][3] In 1851, Nicolay Nicolaysen was a founding member of the Society for the Preservation of Ancient Norwegian Monuments, of which he was president from 1851 to 1899.

He also took active part in the restoration of the Nidaros Cathedral in Trondheim and of the Hall of Haakon IV (Håkonshallen) in Bergen.

[4][5] In 1852, Nicolaysen led the first investigations at the Borre mound cemetery (Borrehaugene) at Horten, Vestfold.

The excavations uncovered an extensive selection of craft work of a stylistic form which has subsequently become known as the Borre style.

Many of the artefacts recovered during these excavations are presently on display at the Viking Ship Museum in Oslo.