20 I I The the Brocken The Brocken I 21 Brocken summit in 1983 10 Bog Bogs are very sensitive habitats in which numerous specialists of the plant and animal kingdom are at home. Small-scale slope bogs, as at this location, are spread in a mosaic among the mountain spruce forest of the Brocken. Slope bogs are mostly young, always lying on slopes, and relatively low nutrient, acidic ground water flowing through them. A water confining ground layer at a shallow depth (here the granite) and large amounts of precipitation are the conditions for their creation. Particularly striking are the white seed heads of common cottongrass in summer. On closer inspection one can also recognize cranberry, bog bilberry, bog rosemary and crowberry that occur in drier areas such as the edges of the slope bog. Particularly difficult to discover is the round-leaved sundew which is hiding among the sphagnum moss. In intact bogs the main plant species are sphagnum mosses, which have an enormous water storage capacity. There are about 25 different species of them in the Harz Mountains. In the National Park the bogs are growing even today. For their protection it is particularly important to only walk on the signposted paths. 11 Building development on the Brocken The history of the Brocken is particularly reflected in its building development. Erected in 1736, for a long time Clouds Hut was the only shelter for tired walkers. In 1800, the first inn came into operation on the summit, and thus the tradition of the Brocken hosts began, and an observation tower was built. The inn was gradually converted into the Brocken Hotel, but this was destroyed by a US air strike in 1945. In addition to Brocken Garden, founded in 1890, the Brocken summit is home to the oldest German weather station (1895) and one of the first television towers in Germany (1938). The proportion of built-up area grew continuously to its 1990 level. Thus the sealed area increased from 120 m 2 in 1800 to 53,000 m 2 . In terms of buildings, there was a 3.60-metre-high concrete wall around the Brocken and in particular the limestone rubble from the roads and barrack areas, of which about 20,000 t was removed in 1990. With the establishment of the National Park and its programme for the restoration of the Brocken, the constructed area was reduced to about 10,000 m 2 . The Brocken wall and military barracks have been removed and the Brocken flora has taken hold again. At the highest point of the mountain you will find the „Brockenuhr“, a 30 m in diameter ring consisting of 48 bronze signs around a rock made of six granite boulders.