Why did Catherine the Great erect a monument to Peter the Great?

Catherine II wanted to demonstrate the succession from Peter I after a series of inconspicuous emperors and empresses. Peter II was too young, she overthrew Peter III herself, Elizabeth I and Anna Ioannovna were illiterate against the background of Catherine.
It was Peter I who proclaimed Russia an empire, created a modern army and navy, which were very useful to Catherine for the war with Turkey in 1768-1774. He achieved access to the Baltic, and Catherine II accomplished the same in the south, with the Black Sea region and the Crimea. Overall, they were both the most prominent rulers of Russia in the 18th century.