Complex sentence: Although it was a public forest, there were still an active forestry going on until around the year 1800, where the large oaks of Riis Skov, was used for quay-building in the Aarhus harbour.
Split into simpler sentences: Although it was a public forest there were still an active forestry going on. Until around 1800, the large oaks of Riis Skov, was used for quay-building in the Aarhus harbour.