The building highlights new architectural values as part of the first Universal Exhibition. It consists of a large dining room and a cafe on the ground floor, a rectangular box with folded façades, so that the exterior image of the building is modeled independently of the interior requirements. The four corners are highlighted by four towers with different crowns. The structure responds to a rigorous application of the brick and iron factory, protagonists of the new architecture. The relationship between the ornamentation and the structure is also clearly resolved: the battlements of the outer wall surround the building accompanied by glazed ceramic shields with airtight inscriptions. This is the first building-manifesto of modernism, which shows some guidelines that later other architects will apply to more complex programs.
For the 1888 Barcelona Universal Exhibition, Domènech was commissioned to build a large Café-Restaurant in the Parc de la Ciutadella.
The building was to be permanent, unlike the rest of the pavilions at the Exhibition, which were temporary.
The Executive Commission that managed the Exhibition liked it very much, because it had original construction solutions and decorative finishes (reinterpreting peninsular artistic styles), like a good modern construction.
Because of the medieval air the building had, it was named ‘El Castell dels Tres Dragons’, a well-known comedy written by Serafí Pitarra (Frederic Soler) a few years earlier.
The project was completed in a very short time, and work began immediately afterwards, but several problems during its construction left it unfinished, especially in the ornamental finishes.
Domènech ended up renouncing the commission rather than hand the work over to the tenant and see how he acted as he pleased. Josep Forteza, who until then had been the assistant architect, was commissioned to continue the work.
The building has a rectangular, four-sided shape, flanked by square towers at the corners. Two of these towers rotate towards a polygonal shape and the tower of homage is crowned with a wrought-iron and glass crown. There is an extension on the ground floor with two large segmental arches and a terrace at the top. The interior is a single nave, divided into ground floor and first floor. The exterior appearance, with walls made of exposed brick and topped with battlements, is reminiscent of a medieval castle. But the ingenious interior structure recovers the Mudéjar building tradition of double walls, like the towers of Teruel, combined with Gothic buttresses.
The façades are built with two very slender sheets of brick, separated by a one-metre wide walkable space, which, thanks to the numerous connecting sheets and the metal braces, create a very stable whole with very little material.
This system makes construction cheaper and quicker, but this constructive daring generated doubts within the construction monitoring committee about its solidity, and they even asked for structural verification calculations of the solution.
Inside, the majestic 18-metre-high first-floor hall is covered with diaphragm arches, a traditional feature of Catalan Gothic architecture, but in this case they are made of metal latticework and are exposed, as Viollet-le-Duc proposed.
Although Domènech's project drawings showed the building to be profusely decorated, in the end only a few stained-glass windows, a frieze of ceramic coats of arms under the cornice and yellow glazed ceramics on the battlements were made.
The walls and ceilings were later decorated with paintings.
Once the Universal Exhibition was over, it lost its use as a banqueting hall and restaurant and the building was abandoned.
Later it became an exhibition hall, music school, Museum of Catalonia, Museum of Biology, school bus centre, Municipal Labour Exchange, Social Assistance and finally, from 1940 to 2000, Museum of Zoology (and later of Natural Sciences). It is not currently open to the public.
