The History of the Construction of the Great Rock

In June 1909, 43 years after the Animal and Plant Naturalization Society was founded, the capital took possession of the Zoo with the aim of establishing new animal demonstration areas and buildings - a modern zoo in line with the thinking of the time, the popularity of which had declined over the previous decade. The general assembly of the municipal board of the Capital voted to offer 1,212,000 then later 1,788,000 kroner for the developments, electing a committee at the same time for directing the works. Dr Adolf Lendl was appointed for reviewing and inspecting the zoological work and Dr Kornél Neuschloss for the construction and technical works. The engineering work for the transforming the area of the garden was carried out by the engineer Gyula Végh, who with Károly Kós and Dezső Zrumeczky had the new buildings designed by several participating young architects. Ilsemann Keresztély, the Director of the Garden took a role in the transformation of the park and in the establishment of the long desired Palm House. In order for the area to appear larger and to show the animals in an environment similar to that of their natural habitat, the construction of two artificial rocks, at the time named Hill “A” and Hill “B”, were also included in the ideas. Hill “A” is in the shape of a limestone range with a dolomite peak; its area is 4,700 square meters with an internal space of 38,850 m3. Two 1:200 scale models were made of the rocks for the planning and design phase, and for the construction work further models in more detail on a 1:25 meter scale. In order to find the correct ratio, a scale model was also made for the whole of the planned garden.

The shape of the hill defined the reinforced concrete frame holding up the shell. The task was to connect the points in space and to create statically purposeful shapes that fitted onto these. Amongst the different structural solutions, the dome and the spatial trusses suggest the wooden frame form solution applied by Karl Hagenbeck, previously director of the Berlin Zoo, and the constructions of the different supporting walls as well as the curved supports suggest an enthusiastic experimenting mood. In addition the structure had to be scaled for the public that conquered the ridge and also the snow load, as well as the soil that was used on the plateau between the two peaks (20 m and 34 m). The central inner space with a 31.80 m tension length and the suspended dome above it was unique in its own right at the time. Its height at the protective collar reached 16.80 m. The form of the eight curved main girders followed the thrust line; therefore the load on the rings holding them together was minimal. The basal ring was even omitted with the foundations sufficiently reinforced instead. The staggered design of the external surfaces of the supports enabled the joining of the posts and beams of the spatial trusses.

The construction commenced in 1909. The work was awarded in a tender to György Pohl’s company. The rock was continuously built by 150-220 people for 3 years, fifty of them alone carried out the shuttering works, with eight thousand cubic meters of concrete being used. The progress of the support was continuously followed by the construction of the outer shell. Cantilever beams and steels that projected from the reinforced concrete scaffolding were used for supporting the hill’s covering shell. This was made of 6-12 centimetres of a Portland cement wire latticestructure (3.5 parts Danube sand, 1 part Portland cement) covering nineteen thousand m2 with pig hair mixed into the mortar to achieve better plasticity. Fine particle concrete was applied to the scaffolding.

The drainage for the rock was developed with great care, applying impermeable concrete to the sensitive areas. In order to prevent cracking in the rocks, expansion joints were included in many places in a way that they would appear to the external observer as natural formations. The foundation, due to the high water table, was from compacted concrete with the walls and floors of the pens of reinforced concrete to prevent the animals from scraping their way through it.

Leaks, internal condensation and damage from World War II together with their poor restoration, as well as the erosion and the corrosive effect of the air pollution of several decades all damaged the support and crustal structure of the rock. On the surface of the crumbling concrete pitting and cracks appeared as well as corrosion of the reinforced steel surfaces. Despite all this the support structure remained in adequate condition until the 21st century. However the shell structure became largely carbonated and full renovation became unavoidable by the turn of the millennia. During the wide ranging renovation works that were carried out between 2006 and 2008, care had to be taken to ensure the external surface remained waterproof and to provide for ventilation of the inner spaces.

The rocks were the most modern animal display spaces of their time

The story of the use of the artificial rocks in the zoo, as animal enclosures started in Zürich. Urs Eggenschwiler, a sculptor who befriended the animals in Zürich designed an artificial rock for the Zürich Zoo. The plan was not implemented there, however the idea appealed to Karl Hagenbeck, the director of the Hamburg Zoo and so the first zoo artificial rocks were built in the Hamburg Stellingen Zoo with the application of the “panorama-display”. The idea then was taken up by several zoos at the time, and was also the case in Budapest. This was supported by a visit of the members of the “Zoo Building Committee” prior to the great reconstructions of 1909-1912, to Hamburg as part of a study tour.

In those few places, where the artificial rocks still survive today, they are treasured as the specialities of previous times from Hamburg to Antwerp and from Barcelona to Buenos Aires. However artificial rock hills of similar size to the ones in Budapest are only found in the Vincennes Zoo in Paris. These were made two decades later and were opened in 1931 with the highest peak; their “Great Rock” at 72 m. In the inside however there are no really usable spaces; neither does the finish of its surface show such details as those in Budapest. Its reconstruction was completed in 1997.

The Hungarian Royal Institute of Geology provided expert guidelines for the preparation of the patterns of the artificial rock and for shaping the granite, gneiss, limestone, dolomite, sandstone, basalt and trachyte stones. A geologist and a sculptor was said to have directed the foremen at the construction and in order for the work to resemble a natural cliff as much as possible, photos and surveys of the “Egyeskő” peak in Transylvania served as a model.

In the Budapest Zoo the role of the rocks was partially to create an aesthetic, nature like display of the animals, as well as to develop exhibition spaces that were considered most modern at the time. Their most important function however was to optically divide the area that was already constrained and to provide an extended walkway. Everybody is surprised that it is only 10 hectares that can be viewed by visitors in Budapest. The Gardens are perceived as a much larger space when walking around than in reality, thanks to the artificial rocks and successful landscaping.

The display concept of the newly restored Zoo was developed by Dr Adolf Lendl. In connection with determining the location of the animal houses and runs he himself wrote: “…species more similar and belonging to each other were put together according to families and orders, as it is required by scientific taxonomy.” Lendl’s concept that was considered modern a hundred years ago has been since re-evaluated and the Zoo successfully rid itself of the previous “menagerie” image. More than this, it has developed into a complex cultural institute. Not only because the collection living there is no longer organised on a taxonomic or “stamp collecting” basis, but in addition to the animal and plant species, ecological units are also displayed. It has progressed far beyond this and has developed significant services in the fields of the arts, education or other areas of culture. The menagerie – zoo – animal park – bio park – eco park evolutionary steps have also been walked by the profession in Budapest, however the circumstances, the location, the demands of the audience and the institutional traditions require a different approach. Ecological display today is an accepted objective; animal and plant species living in a geographical unit or in similar biotopes are displayed closer together. There are clear directing ideas, which emphasis this modern message. Besides the live exhibitions such ideas are for example for the Zoo to be a model for environment friendly operation or to suitably preserve its unique architectural and artistic values and traditions.

The future of the Great Rock: a special exhibition space

By the utilisation of the inside of the Rock, the Zoo that has been struggling with a small site, will gain several thousand square meters of new exhibition area and a worthy area for cultural programmes, events and conferences. The special circumstances, e.g. the spatial structure with its unusual ambiance and absence of natural light, require the installation of special functions or the positioning of a dedicated structure. In addition to the construction of the inner side of the Great Rock, plans have also been drawn up to have the majority of the former high standard buildings in the vicinity renovated.

The creation and furnishing of the inner space of the Great Rock into an exhibition space, the century old dream of Adolf Lendl can finally become a reality.