On the edge of the Mirror Pond in the Catherine Park stands the Upper Bathhouse pavilion that was constructed in 1777–79 by the architects Vasily and Ilya Neyelov.

The Upper Bathhouse was designed in the early Classical style. Although the facades of the pavilion are almost devoid of decorative embellishments, it creates an impression thanks to the proportional relationship of the main body and the three-sided projection that protrudes  towards the pond. The walls of the projection are pierced below by arched windows and a broad doorway and above by round windows. The building is crowned by a balustraded parapet.

The Upper Bathhouse is particularly attractive when viewed from the central alley of the Old Garden (the Regular Park). The façade of the pavilion, sharply set off by the foliage behind, completes the vista of the pond, in whose mirror surface its light yellow walls are reflected.

Until the middle of the nineteenth century the Upper Bathhouse retained its original function and contained six rooms: an entrance hall, changing room, bath, steam bath, boiler-room and an octagonal central hall for relaxation.

The ceiling and walls of the central hall were painted by Alexei Belsky from engravings made by the artist Franciszek Smuglewicz and the architect Vincenzo Brenna of the murals in the Golden House, Nero’s palace in Rome.

The Upper Bathhouse was destroyed during the war and restored in 1952–53. The ceiling painting and two overdoor compositions in the main hall depict as before scenes from the ancient myth of Phaethon, the son of the Sun god. The polychrome wall painting that was recreated at that same time employs motifs of garlands, flowers and fruit, which invests the interior with a festive elegance.

At present the pavilion is used for temporary exhibitions.