I found this place on Wikimapia:
LINK and went to take a look - even in todays -10°C and park covered in snow, the bookcase was there and some books in it as well.
The place was not registered on bookcrossing.com, so I bought a book of short stories of my favorite Russian fantasy author V. Vasilev and returned the other day to release it. Browsed through the books in the bookcase, didn't find anything interesting there - mostly outdated computing literature.