Even after the design change, the station's construction was plagued by difficulties. Quicksand from between the two layers of clay began to seep into the construction site almost immediately, and due to the unexpected softness of the Carboniferous clay the station began to slowly sink. Nevertheless, the builders of the station were able to surmount these problems and Lubyanka was opened as planned on May 15, 1935. The heroic efforts of the Metro builders are memorialized in a sculptural composition in the vestibule on Nikolskaya street.