in Russia, the Petrodvorets watch factory. Six months were necessary for the development and installation of the clock by a group of engineers from the watch factory "Raketa". The clock's mechanism weighs 4.5 tons and consists of 5000 pieces in steel, aluminum, titanium and gold-plated metal. The mechanism has a height of 13 meters and a width of 7 meters. It consists of 21 large gears and a 13 meters pendulum. The pendulum surface acts as aspheric mirror, creating an optical effect. The main mechanism of the clock is on the fifth floor. It is the largest clock mechanism in the world and it is among the five largest mechanical clocks in the world such as Big Ben, the carillon of the Moscow Kremlin, the clock on the "Clock Tower" in Prague or of the clock of the city of Ganzhou. Architecture and design The building of the Central Children's Store with total area of 73 thousand square meters occupies a quarter in a lively tourist location - between Lubyanka Square, Teatralny Drive, Rozhdestvenka Street and Pushechnaya Street. There are public entrances into the building from each side. One of the exits from the nearest Lubyanka metro station is historic and terminates directly into the shopping mall building. Prior to the renovation only 4 floors of the building were commercial, the remaining space was used for warehouses, crafts stores and administrative premises. After renovation the total leasable area increased from 19 to 34 thousand square meters hosting over 200 stores with a full range of baby and child products as entertainment, dining and other services. The elevation of the dome of the central atrium was increased from the level of the 3rd to the 7th floor. At present the building features 24 escalators and 22 elevators and 24 hour underground parking. The concept of the shopping mall Within the edutainment concept the following activities can be found: Cyber-sports club Winstrike Arena - a multifunctional cyber-entertainment zone, equipped with advanced computer equipment Europe's largest amusement park of virtual and augmented reality Arena Space Kidburg family entertainment centre allowing children to role play adult jobs and earn currency - a model of the adult world for children from 1.5 to 14 years old Fantastic entertainment center Zyrkus featuring a 5D dome cinema and playgrounds equipped with immersive technologies, combining the real world and digital content Multimedia amusement park "Alice - Return to