The Rhine romanticism was the interpretation of the landscape conditions and history of the Rhine Valley in the cultural-historical period of the romanticism, by the end of the 18th century until the late 19th century and was continued in all forms of art expression. Schlegel's travel notes as a significant contribution In response to the nascent industrialization with their perceived negative side effects, artists and writers turned to nature and the past. Friedrich Schlegel describes his impressions of a journey along the Rhine in 1806: "For me only those areas are beautiful, which are usually called the rough and wild, since only these are exalted, only exalted areas can be beautiful, only these excite the thoughts of nature. [...] But nothing is able to embellish and to increase the impression as much as the traces of human courage in the ruins of nature, bold castles atop wild rocks – monuments of the time of human heroes harking back to those higher heroic days of nature. Lord Byron made the Rhine area enormously popular in England in 1818 with his verse narrative, Childe Harold's Pilgrimage. The German poet Adelheid of Stolterfoth created numerous Rhine poems. In the visual arts William Turner drew attention to the Rhine, especially in England, with his paintings, which were the result of several cruises on the river. The most popular romantic Rhine views, the reproductions in varying formats, such as postcards spreads were derived from Nikolai von Astudin. From a tourist stopover to a tourist destination The Rhine Gorge was depicted by late 18th century travellers like the Italian Aurelio de' Giorgi Bertola (first travelogue in the romantic style) in 1795 and the British John Gardnor (etchings), who both traveled the gorge in 1787. In 1802, Clemens Brentano and Ludwig Achim von Arnim toured the valley, which was developing from a region one passed through on the Grand Tour to Italy into a first rank tourist destination in its own right. After Switzerland, with its rugged mountain valleys, the rocky Upper Middle Rhine Valley with its many ruins became a "must" for tourists. Many princes and wealthy individuals began to rebuild the castles; foremost among these was the Prussian royal house, which was building at multiple locations simultaneously. The most outstanding work of the Romantic Rhine is Stolzenfels Castle, built by King Frederick William IV of Prussia in Koblenz. Even absolutely secular constructions, such as tunnel