You will be talking about "The Garden Of Cosmic Speculation" near Dumfries in South West Scotland, Katarina. Unfortunately it is a private garden and not normally open to the public but I do know that they take private parties by arrangement.
Try this link:
http://www.gardensofscotland.org/garden.aspx?id=9e9630a6-2554-431a-9448-9ee200c08aee

Dear David,

thank you very much for your answer. What a pity, it is a private territory. I heard about this architect that he also made gardens for people with cancer, so I thought this one is also opened to public.
May I ask you - I noticed to me unknown flag at your profile. Where are you from?

Katarina, naughty you, that is the flag of SCOTLAND! :-). I live in the diagonaly opposite corner of Scotland to this garden.
Whilst it is a private garden a direct enquiry can often be sucessful. Try contacting them and say that you are coming from Slovakia, you just might get a private invitation.

Lol. Well, one learn all his/her life. I did not know that you still have your own flag! Might be one day I will be free and I will come. At least as a leaf. Lol.