The development of the Wałbrzych Palm House property (Palmiarnia), which took place between 1911 and 1914 at the initiative of Prince Hans Heinrich XV. The centrepiece of the facility was the 15-metre Palm House, built of metal and glass, in which date palms were cultivated. The whole property was surrounded by one-storey orangeries. The Palm House’s most remarkable feature, however, was the building material lining its interior: solidified lava from Mt. Etna, which the Prince had brought from Sicily in seven train wagons. The builders smashed chunks of the volcanic tuff into smaller pieces, and made grottos, waterfalls and walls with nooks for plants. The effect of this work may be admired to this day. Over 250 species of plants now grow on the Palm House grounds, representing the flora of various climatic zones and almost every continent. It is worth viewing, among others, the Asian bamboo plants, ficus trees and bushbushes; the Australian eucalyptus, spruce and pine trees.