In the regular area of the Catherine Park not far from the Upper Bathhouse stands the Lower Bathhouse. This pavilion, situated aside from the alleys of the park and intended for use by members of the court, was built to the design of the architect Ilya Neyelov in 1778–79. Its façade is half concealed from strollers in the garden by trees and shrubs.
The Lower Bathhouse contains ten rooms grouped around a central hall with a large round bathtub. The water was heated in two boiler-rooms that had separate entrances and delivered by pipes to the steam-room and the rooms with baths.
The unusual layout of the pavilion determined its external appearance. Two of its facades – looking towards the palace and directly away from it – are identical, but neither is the main one. The walls of the central hall are raised considerably higher than those of the side room and form a windowed drum supporting the dome that crowns the building. Both the drum and the façade walls contain round windows that are placed high up in accordance with the functional purpose of the building.
The internal décor of the Lower Bathhouse has not survived. From archive documents we know that some of the rooms had ornamental painting on the walls and ceiling, that the relaxation and changing rooms were heated by marble fireplaces and that the circular bath was surrounded by a balustrade.
The facades of the pavilion suffered little during the Second World War and were restored in 1944–45. In July 2011, first time since 1917, after a long restoration work the Lower Bathhouse interiors finally opened to public with the exhibit Court Bath in the 21st century.