The Fellin Manor was managed by August Paul Adolph's son, Oswald Paul Conrad Constantin, who married a baroness Emily Sophie Alexandrine von Wolff in Latvia in 1877.

Right after the wedding the planning of a new manor house in Viljandi started. The baron's firstborn, daughter Alexandrine Alice Emily was born in the old building of Fellin Manor in 1878. Alexandrine (later von Mensenkampff) writes in her memories that she was a great disappointment as her parents expected to have a son first. But Alexandrine’s energetic and active, somewhat boyish nature helped the parents to come to terms with that “shortfall”: her playmates were horses and dogs, she spent most of her days outdoors and in the garden, and she felt particularly proud when her father took her on his business trips. On these trips, the father introduced his daughter to the secrets of agriculture and they discussed business plans together.

The new Renaissance Revival-style stone manor house was completed in 1880 to the design by the architect Friedrich Ferdinand Modi. According to contemporaries, the manor house was beautiful, as was the surrounding park with its abundant greenery.

The main entrance of Viljandi Castle. Photograph from the early 1900s. Estonian History Museum SA

Alexandrine has written in her childhood memories that the favourite place of the castle people in the summer was the spacious porch, where they worked, read, ate lunch, drank coffee. It was also where her playground with a swinghorse and dolls was. A large Venetian chandelier hung from the ceiling of the hall with beautiful polished elmwood doors, and on the walls there were many works of art, including copies of the paintings by Murillo, “The Infant St John with a Lamb” and “The Infant Christ and Saint John the Baptist with a Shell”, some Italian and Dutch sea paintings and a large winter landscape. In the corner of the room, on the dressing table stood a Goethe bust, that the child had dropped during the move, thus damaging the bust’s nose. There were also several paintings on the walls of small drawing room, including two copies of Rembrandt. The mother's writing room was also on the same floor, with lots of photos on the walls and a marble relief by Weizenberg of her parents. In the big bedroom of the parents there was an interesting mirrored wardrobe, exciting for the child to explore, because her mother used to hide Christmas presents in there. The child's room, the maid's room, the cooking and dining room, the gentlemen's salon, the father's writing room, the buffet room and the back porch were all on the same floor. A large wide staircase led to the top floor, where there were seven guest rooms and a large bright loft for drying laundry.

Another steep staircase led to the top attic, where old bottles, boxes and crates were stored, which the child happily used for building doll houses and stables. Alexandrine loved to go there to look out and far into the wild from the small round windows.

On the basement floor there were several dry cellars, a servants’ room, a handicraft room and a laundry room.