He also played an important role in the establishment of the Royal Danish Academy of Art (Det Kongelige Danske Kunstakademi), and was its first native-born leader.
[1] [2] He was born Niels Madsen on the farm in the village of Egtved in the parish of Haraldsted on the island of Zealand, Denmark to Mads Nielsen and Dorthe Hansdatter.
[1] From 1725 he lived in Warsaw, Poland, where he came to the attention of German architect and draughtsman Colonel Matthäus Daniel Pöppelmann, for whom he worked for several years.
[3] Eigtved came into a rich architectural environment, which was influenced by the presence of French immigrants including Jean de Bodt and Zacharias Longuelune.
He made excellent military drawings, and became acquainted with Danish statesman General Poul Vendelbo Løvenørn, who after his return to Denmark interested King Christian VI in Eigtved.
[8] Thus began a lifelong rivalry with colleague Lauritz de Thurah, another royal building master and the leading proponent of baroque architecture at the time.
[9] He participated along with German architect Elias David Hausser and Lauritz de Thurah in the interior construction of Christiansborg Palace, with wood sculpting by Louis August le Clerc.
Eigtved designed the king's apartments, the main staircase, the chapel's interior, the riding grounds, and the Marble Bridge (Marmorbroen) and its two pavilions, and gave the castle its delicate Louis XIV style.
[10] In 1742 Eigtved was promoted to lieutenant colonel in the Engineer Corps, became a member of the Building Commission, and took over the role of leading architect for Christiansborg Palace from Hausser.
Credited with being the earlier example of "maison de plaisance" in Denmark, "it jointly had large and small rooms symmetrically ordered around the main axis' vestibule and constervatory.
The mansard roof is the result of an alteration carried out by Johann Gottfried Rosenberg in 1752–1753, who while working on Frederiksdal also designed Margård Manor on Funen, also inspired by French country estates.
In late summer 1748 the Academy moved to the floor above the Crown Prince's stables at Christiansborg Palace, where Eigtved also had his official offices.
In the middle of the plaza, Moltke's Danish Asia Company erected a monumental equestrian statue of Frederick VI designed by Jacques François Joseph Saly.
The palaces were finally completed in 1760. de Thurah tried unsuccessfully to get project leadership of the work on Frederick's Church, but was denied that role, which went instead to Nicolas-Henri Jardin on 1 April 1756.
Eigtved also built Sophienberg in Rungsted, the old Royal Danish Teatre, and in 1753 helped extend Fredensborg Palace by adding four symmetrically positioned corner pavilions with separate copper pyramid-shaped roofs to the main building.