Joanna,
Yes comparing the two photos, it is the same palace. I like the details in the URL you posted.
Now if we can only see a photo of Felix's grandmother's house at 42 Liteyny. I have seen interior pictures in The Hidden Interiors, but I still would like to see the building itself. It is currently used by the organization Znaniye (Knowledge), and I wonder if anyone has a picture?
BobG