The Drachenfels ("Dragon's Rock", German pronunciation: [ˈdʁaxənˌfɛls]) is a hill (321 metres (1,053 ft)) in the Siebengebirge uplands between Königswinter and Bad Honnef in Germany. The hill was formed by rising magma that could not break through to the surface, and then cooled and became solid underneath. It is the subject of much tourism and romanticism in the North Rhine-Westphalia area.
The ruined castle Burg Drachenfels, on the summit of the hill, was built between 1138 and 1167 by Archbishop Arnold I of Cologne and bears the same name. It was originally intended for the protection of the Cologne region from any assault from the south. Originally it consisted of a bergfried with court, chapel and living quarters for servants. The castle was slighted in 1634, during the Thirty Years' War, by the Protestant Swedes and never rebuilt. As a strategic asset it had outlived its usefulness. Erosion due to the continued quarrying undermined much of the remains and only a small part is left today.
The rock, like the rest of the Siebengebirge, is formed by the remnants of a volcano and has been the site of a trachyte quarry since Roman times, which, amongst others, delivered the building material for the Cologne Cathedral. Of all the hills in the Siebengebirge, it is closest to the river Rhine, which facilitates easy transport by barges, thus making it an excellent place for a quarry. Quarrying ended in 1836, when the Prussian government bought the quarry. In 1922 the first protection measures were put in place and in 1956 the site was declared a national park.