I was passing through St Pancras station today and noticed a Lego Christmas tree. From a distance it does not really look like Lego:
As you get closer, the construction is more noticeable:
and if you look inside it, the tree illusion disappears and it just looks like a curious Lego construction in green and brown. Someone put a lot of work into this.
Update: according to this article it is “the world’s largest Lego Christmas tree”, contains 600,000 bricks and 172 branches, and took two months to complete. Thanks to Peter Ibbotson for the link (see comment).