from the central part by way of expansion joints. Tying up of the foundations, the existing part and the new structure of forthcoming stages were achieved with reinforced concrete columns and tie-beams. Expansion joints in the wing sections were carried out along the line of intersection between the semi-domes and the main arches, and vertically down the bell towers up to the foundations. The continued construction was designed as a fully prefabricated reinforced concrete element structure. From the geometrically complicated form in view of its structural points, the single elements had to be broken down into precast components outlined with straight lines to the greatest possible extent. Walls had been designed as hollow boxes, which, when assembled, give the building its massive appearance. All arched shapes of the galleries and vaults were transformed into assemblies of elements curved into two dimensions, which, having been erected, formed three-dimensional shapes. The semi-domes and the dome have been linearized by designing a system of arched trusses and two layers of curved decking. The precast parts were bound into a whole by in-situ cast parts of the structure which provided the required safety and longevity of the building. The bell towers were initially started as a combination of brick and concrete columns and were continued as concrete box-structures for providing the greatest possible resistance of the towers and the least possible weight. This part of the building was completed by applying the sliding shuttering method (slip-form), with the advantages of prefabrication. The central part of the building includes four main arches between the bell towers and the central dome with the pendentive underneath and the dome on top. Each arch spans 24 m, which is one of the widest vault spans achieved, as most of the European great domes rest on 8 or 16 pillars. Only Hagia Sophia's dome rests on only four pillars with a span between the arches reaching 31 m. It is still the widest span between the arches of any historical sacral building and still the biggest dome which was erected on only four pillars. It was found that the type of foundation chosen in the initial design lacked adequate strength to carry the loads imposed from the whole building. With the new materials and design methods, weight was reduced by 30-40 %. Before the lifting of the main dome the "Simplex" piles below the main tower-column had to be