Beautiful stairs for a Beautiful Sunday

I hadn't planned to meet the Beautiful when I turned into an alleyway on the Moyka River Embankment. I just saw an open gate and decided to look around a place I hadn't visited before.

The mansion was built in the 19th century and is now owned by the Union of Architects. The front entrance to the building is on the side of Bolshaya Morskaya Street. The high windows of the front rooms were well lit, behind the windows was visible lush interior of the front rooms.

A side door caught my eye, it was hospitably open. The door is beautiful, and in a modern building it would be a grand entrance, but in this building the door leads to a service staircase. These stairs are also called "back stairs" because they were used for household "dirty" jobs: to bring water and firewood to the rooms. I wasn't expecting any architectural revelations from this staircase, but I decided to go in and take a look. This is what I saw from the entrance:

The photo is a little dark, but the overall impression is conveyed. This staircase is intricately shaped and made of cast-iron openwork steps. On the first floors, the smooth turns and curves of the staircase bring to mind the enormous popularity of the Art Nouveau style in the early 20th century.

Above the form of the staircase becomes a little easier, the curves disappear and there are the usual turns of staircases, but the openwork steps and staircase railing pattern is maintained until the top.