Some of the most awesome books I fondly remember from my childhood are Soviet ones. One awesome thing about those books were that they were translated to regional language and were printed/typeset in equally high quality papers and hard bound as the original. One reason most comments here are able to relate with the post is because those books were accessible to them in their mother tongue. Russia/India did a fabulous job in translating those books to Indian languages and still maintain high quality print and typeset. Unlike now in those days English language was not accessible so all the education and learning was in the child's mother tongue.

Physics for Entertainment -- Yakov Perelman [1] is one such book.

[1] https://www.amazon.in/Physics-Entertainment-Book-Yakov-Perel...