Kruhzolzalnye Ponds, Upper Kruhzolzal Pond, St. Petersburg, Russia, 196625
The Round Hall, a pavilion of classical architecture, is located in the park area of Bolshaya Zvezda at the intersection of radially arranged roads, where originally on a circular platform, sometimes called by the French name Tapis Vert (Green Carpet), there was an observation deck.
The pavilion was apparently conceived by Cameron but not completed – his interior decoration project from 1799 was not approved. Two drawings of the hall’s interior decoration have been preserved in the Palace Museum; one, with almost erased pencil notes in English, dated modestly inscribed in the ornament above the mirror and showing all the features of Cameron’s weak, uneven drawing style, the other with a confident, strong manner, strikingly sketched and boldly signed by Brenna. One is in the style of the Catherine era, the other with all the characteristics of early 19th-century classicism. Pavel approved Brenna’s project, which was executed. The pavilion was built in 1800 for 10,000 rubles.
An inventory of “all the furniture contained therein” has been preserved. Here, among the listed sofas, lanterns, curtains, and other furnishings, there are also noted four alabaster busts and four statues, and in the Academy of Arts registry from November 10, 1800, statues just delivered to Pavlovsk are listed: “Venus Medici” – 35 rubles, “Apollo” 30, “Faun with plates” – 30, “Mercury” – 30, and busts of “Genius, Minerva, Romulus, and Achilles,” each 5 rubles. These statues and busts have not survived to our time.
“The Round Hall, or, according to early 19th-century inventories, the New Hall, stands alone and open on the middle platform of Bolshaya Zvezda, at the crossroads of its twelve roads-clearings. During the lifetime of Maria Feodorovna, the Round Hall was known as the music salon (its French name “Salon de musique” was colloquially called “Salty Peasant”), and concerts, dance evenings, and festive dinners were held there; later, under Mikhail Pavlovich, when the railway was laid, a restaurant-café was opened here, and in winter – a buffet by the toboggan slides.

Since 1917 the pavilion has been closed, but in spring 1922, through a broken door, the mirror above the fireplace was stolen.” During the Great Patriotic War, the pavilion was considerably damaged and restored in the 1960s.

Currently, it has been restored to its function as a music salon, where chamber concerts are held on weekends.
Sources:
https://www.citywalls.ru/house25620.html
https://pavlovskmuseum.ru/about/park/layout/41/1155/