Its old, because we are looking at old photos, lost because a lot of buildings to be seen here exist no more, and found, well, because we have found the photos, usually somewhere on the web.
I collected some photos to start off with, but you’ll quickly notice a Scandi-bias, its just easier for me to research as I know what to look for. So Balts, and to a lesser extent, Finns, I am relying on you guys to find stuff.
Please feel free to add anything related to the topic and to add to the short explanations given by me.
maps, sketches, unrealized projects, photos, the very old, the very recent. Before and now comparisons, all is welcome.
We start with Copenhagen and Christiansborg Slot including its predecessor København Slot

The first castle on the site was Absalon’s Castle, built in 1167. This image from 1698, however, shows Copenhagen Castle built after Absalon’s was destroyed by the Hansa League in 1369. The castle was rebuilt several times. Christian IV, for example, added a spire to the large entrance tower, which under the name of the Blue Tower gained a reputation as a prison.

In the 1720s, Frederik IV entirely rebuilt the castle, but it became so heavy that the walls began to give way and to crack.

King Christian VI commissioned architect Elias David Häusser to build the first Christiansborg Palace and in 1733 work started on the magnificent baroque palace.

By 1738, work on the main palace had progressed so far that it was possible to start on the other buildings included in the total project. The palace included show grounds and chapel.

Most of the palace complex was completed in 1745

The palace and church were ruined by a fire in 1794, but the showgrounds were saved.

From then on, the royal family lived in temporary accommodations at Rosenborg Castle and later Amalienborg Palace. However, architect Christian Frederik Hansen, was soon called upon to resurrect the palace. Hansen started building the second Christiansborg in 1803 in a French Empire style

By the time the palace was finished in 1828, King Frederik VI had decided he did not want to live there after all, and he only used the royal premises for entertainment. The palace also housed the Parliament and administrative services. Frederik VII was the only monarch to live in the palace. This was between 1852-1863.

The second Christiansborg burned down in 1884. Saved were Hansen’s chapel, the showgrounds, the building linking the palace to the chapel, and the ministerial buildings on Slotsholmsgade.
The third and current Christiansborg was built between 1907 and 1928 by Thorvald Jørgensen in a neo-baroque style that pays lip service to the first Christiansborg. The building is used by the Danish parliament.