After his return home, Thura rose rapidly up the ranks. He became resident engineer in 1732. In 1733 he was named Royal Building Master with supervisory responsibility for royal buildings on
Zealand and on
Lolland-
Falster. At the same time, he was promoted to captain in the Engineering Corps. In 1732–1736, he designed and built the royal palace in
Roskilde, also known as the
Yellow Palace, on the site of the old bishop's palace east of
Roskilde Cathedral. The four-wing baroque building became the headquarters of the
Duke of Wellington during the
English siege of Copenhagen in 1807, and now houses the Museum of Contemporary Art. In 1733–1739, he worked on the first remodelling and expansion of
Hirschholm Palace for King
Christian VI and his consort, Queen
Sophie Magdalene. In 1734–36, de Thurah built the
Eremitage Palace, a palatial hunting lodge overlooking
Jægersborg Dyrehave north of Copenhagen, and facing east over the
Øresund to
Sweden. The grey-stone house with copper-clad
mansard roof replaced another hunting lodge named "
Hubertus", which had been built nearby in the 17th century. The original design featured an elevator-table, similar to a
dumbwaiter, which could be raised from the cellar up to the dining room. In this way, servants stayed in the cellar kitchen, where they prepared and set the table, and then it could be hoisted up to the dining room through a hatch in the floor. Diners would then eat unattended by servants or "
en eremit", that is "in the hermit style". The lodge is still in use to this day for special occasions. But already after only a couple of years' service back in Denmark, Thura began to feel that his baroque style had gone out of fashion. He felt that baroque was losing ground to
rococo, a style mastered by another force in contemporary Danish architectural circles,
Nicolai Eigtved, who would be Thura's colleague and rival throughout most of his career. Eigtved, who returned to Denmark from his travels in 1735, became the king's preferred architect, and Thura felt himself being more and more set to the side. In 1736 Thura was promoted to lieutenant colonel. He participated, along with German architect
Elias David Hausser and Nicolai Eigtved, in the interior construction of
(the first) Christiansbrog Palace. He designed some of the interiors in the Queen's apartments 1737–1740, but these were lost in the fire of 1794. He also created plans for the main staircase, the chapel, the marble bridge, the pavilions and the riding grounds, which were never realised. On 19 October 1740, he married Anna Rosenørn, daughter of a General Major, and was conferred nobility under the name "de Thurah". In 1741, de Thurah elevated the roof of the main building at
Fredensborg Palace. In 1742 he was named to the Building Commission, and took on supervisory responsibility for royal buildings on Zealand and
Funen. In 1743–1744, he designed the final rebuilding of Hirschholm Palace, the most impressive building project of the period, known as "the
Versailles of the North". The same year, work was completed on the tower and spire for the
Church of Our Lady, in Copenhagen, partially after a drawing by
Vincents Lerche. The building, however burned down during the
bombardment of Copenhagen in 1807, and was rebuilt by
Christian Frederik Hansen. In 1744, de Thurah was promoted to colonel. His three-volume work
Den danske Vitruvius was published in 1746–1749, containing almost 400 drawings and measurements of buildings in Copenhagen and royal castles and other interesting buildings in Denmark, with Danish, German and French text. Frustrated by his losing assignments to Eigtved, he petitioned the king in 1747 for a new non-architectural position, but that was rejected. In 1748, de Thurah was asked to assist on the building of a new spire on the
Lambert van Haven designed Church of Our Saviour in the
Christianshavn district of Copenhagen. He chose a design inspired by the
Sant’ivo della Sapienza church he had seen in Rome many years before. The new design however was much more costly than the king's original plan, and this led to a fierce rivalry between de Thurah and Eigtved over the choice of building material. The king finally sided with de Thurah. in Copenhagen, built to his own design in 1755-57 That same year, de Thurah's wife died. He married again, on 16 January 1750, to Christiane Marie de Kiærskiold, heiress to Børglum Kloster. He felt overlooked and pressured by colleague Eigtved, and so he pulled back on his career. He moved out of Copenhagen to the estate at Børglum Monastery in
Jutland with his wife. De Thurah's masterpiece, the ornate, spiral-staircased spire on Our Saviour's Church, topped with globe and figure, was completed in 1752, and can still be seen high-above Christianshavn to this day. In 1753, after his retirement from the Engineering Corps, he was named General Major. That same year he gave up his responsibility for royal buildings on Zealand, that being taken over by Nicolai Eigtved. In 1754, he was named General Building Master, while Eigtved took over as Royal Building Master. The six-years-older Eigtved died that same year, causing de Thurah to be called back into service as the leading architect of the day. De Thurah was assigned the completion of work in Eigtved's
Frederiksstad district centred on
Amalienborg, including the last two palaces on the eastern side of the square, and in 1754–1758 he designed and built the four pavilions at
Frederiks Hospital, now housing the
Danish Museum of Art & Design, which Eigtved had begun in 1752. He also built a house for himself in the district at
25 Amaliegade from 1755 to 1757. , Copenhagen. He also tried to get plans approved for
Frederik's Church, the centerpiece of the Frederiksstad area. He wanted to build a stone dome in the style of
Michelangelo. The work eventually went to French
neoclassical architect
Nicolas-Henri Jardin. He died during the night of 5 September 1759 in Copenhagen, and is buried in
Trinitatis Church. ==Writings==