Suggest me what you consider to be the magnum opus of your country’s literature

The Good Soldier Švejk – Jaromir Hasek (if anything represents czech mentality- it’s this. It’s antiwar and satirical)
The Bougett – Karel Jaromir Erben (dark folk tales and poems ala Edgar Poe
The war with the newts – Karel Capek
R.U.R – Karel Capek
Most famous is unbearable lightness of being – Kundera (but I find it really boring)
Franz Kafka – The Metamorphosis. But there are disputes whether he was Czech. He is czech, bohemian German speaking Jew.