<human>:  Where did the Russian tsar Peter the Great get his nickname?
<bot>: He was nicknamed Peter the Great because he was a great reformer. Peter the Great was the first tsar of Russia who ruled for more than 30 years. He was born in 1672 and died in 1725. He was a great military leader, and his reforms were very successful. He built many cities, including St. Petersburg, and he also made Russia into a major power.