hall which is suitable for lectures is situated in the systematic section within widely spread meadows. Engler and his students used to go there to hold lectures. Water facilities Fresh water is supplied by two deep fountains. To deliver the water, vapour pumps were added and supplied with heat by the heating station. The water was pumped directly to the mains system of the garden as well as to the large water tower located behind the conservatories. The pumping system was designed for a daily output of of water. The technology was updated to make the pumps operated by electricity. The deep well still ensures the water supply networks. Heating facilities Special requirements were placed on the heating facility because of the variety of plants requiring different growing conditions. Continuous operation during night and summer was required for cultivation, so an independent heating facility with three warm water kettles and a boiler was built in the Botanical Garden. The heating facilities had to meet the following challenges: provision of the heating systems with hot water steam and low pressure steam; supply of the greenhouses with water vapour for air humidification and tropical mist; supply of the nursery with warm water; and supply of the pumping station, the rainwater pressure pipe, the electrical lighting and the electrical working machines with energy. Until the decommissioning of the plant, it had been run with approximately of coal a year. The Botanical Garden was connected to the network of the district heating plant on 13 September 1967. Since then it has been the main source for heating energy for the Botanical Garden. Annual energy consumption levels amount to 8,580 gigacalories (Gcal), the equivalent of (kWh), from which a third is used for the Great Pavilion. Its renovation has reduced the energy consumption levels significantly, and when complete, energy consumption levels will be reduced by one-fifth. Bunker The construction of a bunker about below the began in 1943. Access was through two entrances from the courtyard of the Botanical Garden. It was built for the SS Main Economic and Administrative Office which was located about away in 126–135 . The bunker was used for storage of the file inventory and to protect staff during alerts. It was of an unusual layout and construction with only a few rooms and several long tunnels. There was a tunnel shield at the end of one tunnel that remained