CREATE TABLE table_name_51 (place_of_birth VARCHAR(255), elevator VARCHAR(255), elector VARCHAR(255))
What's the Place of birth listed that has an Elevator of ALexander III, and an Elector of Ruggiero Di San Severino?
    
SQL: SELECT place_of_birth FROM table_name_51 WHERE elevator = "alexander iii" AND elector = "ruggiero di san severino"