Pushkin (Tsarskoe Selo) is a popular place both among tourists and among residents of St. Petersburg. Since childhood, I've known all the parks and buildings in Pushkin. A lot of pictures of the archive are dedicated to the details of Pushkin's parks.
Cameron's gallery. It is located in the Catherine Park near the Catherine Palace. Now it's not allowed to go up, as far as I know.
Most likely the pavilion "Hermitage", located in the same Catherine Park. It is located on an artificial island, intended for recreational activities. Now it's tourist's object only.
The door of the pavilion "The Hermitage".