The engineer Scott Russel based his concept for the Rotunda on his design for a 45 metre high dome created for the Great Exhibition of 1851 in London. Although Russel was accused of making structural engineering errors and mistakes in estimating the material involved, Hasenau approved the project and handed responsibility for realising the scheme to the architect Friedrich Schmidt aided by others including the Duisburg-based steel company Johann Caspar Harkort. As predicted, the construction of the roof presented enormous problems which delayed the completion of the building until March 1873.
A total of thirty-two 24 metre high pillars arranged in a circle supported an enormous tension ring with a diameter of 104 metres. This tension ring was first riveted together on the ground before being lifted into place. The ring itself supported 41 metre long radial struts which converged upwards to meet at the pressure ring. The structural elements were emphasised by fixing the skin of the roof beneath the beams. Two lanterns were installed above the sloping part of the roof. The lower one had a diameter of 31 metres and housed a walkway providing visitors to the exhibition with a panoramic view of the whole site and beyond to Vienna and the surrounding area from the impressive height of 70 metres. The second lantern stood high above the roof and was topped by a round dome. The highest point of the building at 85.30 metres - which made it the tallest building in the whole exposition - was a four metre high, five metre wide gilded replica of the imperial crown set with precious stones. An enormous building was thus created as the symbol of the World Exposition. Its monumental dimensions exceeded those of St. Peterís in Rome. A "technological masterpiece", a symbol of the "enormous advancement in engineering", and topped off with a crown - the key expression of the megalomaniac, egotistical fervour of the youthful economic self-confidence of the Austrian Empire. Decorative elements inside the Rotunda were required to "harmonise" with the iron skeleton of the building with the objective of merely underlining the beauty of the structural engineering. The supporting pillars were linked with circular brick arches, whilst the metal skin and the iron pillars were wrapped in jute and decorated with figures. Daylight in generous quantities flooded into the building thanks to the large side windows and the lantern. Four large trees from the former park decorated the centre of the hall along with the magnificent central fountain created by Durenne. A hydraulic lift whisked the visitors to an inner gallery at a height of 23 metres which not only provided a good view of this arena for the finest exhibits and the biggest celebrations, but also gave access to the outside of the building onto the tent roof from where intrepid visitors could mount ladders to climb up to the crown.
|Year: 1873||City: Vienna||Country: Austria|
|Duration: 1st may - 31st october 1873|