You think erecting a memorial to someone like Columbus is setting up an idol?
From the Christian Post: The Bible gives us two important warnings about idols (whatever form they take). First, it warns us that they are false; only God can meet our deepest moral and spiritual needs. Second, it warns us that nothing should take God’s place in our lives. The Bible says, “You shall not make for yourself an idol in the form of anything” (Exodus 20:4).