Complex sentence: Russia became the last European country (excluding Vatican City) to abolish absolutism, and it was the only one to do so as late as the 20th century (the Ottoman Empire drafted its first constitution in 1877).
Split into simpler sentences: Russia became the last European country (excluding Vatican City) to abolish absolutism. The only one to do so as late as the 20th century (the Ottoman Empire drafted its first constitution in 1877).