This is Fredericksborg Castle, a few train stops north of Copenhagen. It was built at the time of Christian IV in the 17th century and restore after a fire in 1859. The castle has been housing Denmark's Museum of National History since 1878.
I went there a few days ago to see photographer Steve McCurry's exhibition in the right wing featuring some of his amazing work including the very iconic 'Afghan Girl' from 1984.
Although this is a beautiful castle the photo itself could easily look boring. I think what makes it a little more captivating is having the birds flying adding interest and movement. There is also an interesting foreground with the frozen front of the lake adding some interesting warm colours and faint reflections.