The phrase 'As old as ___' can be completed with the crossword solutions of ADAM (4 letters), Thehills (8 letters), and METHUSELAH (10 letters). ADAM is the first man in the Bible, created by God in the Garden of Eden. Thehills is a reference to the Hills of Eternity, a place in the Bible where the souls of the righteous go after death. METHUSELAH is the oldest person mentioned in the Bible, living to the age of 969. All three of these answers refer to characters from the Bible who lived for an incredibly long time, thus completing the phrase 'As old as ___'.