The expression "old as Methuselah" is commonly used to describe someone or something that is exceptionally old. However, there are many synonyms for this phrase that can be used to convey the same meaning. One could say "aged as time itself," "well past their prime," "ancient as the hills," "weathered and worn," "vintage," "elderly," or "antique." These words all connote a sense of long-lasting existence and the idea that something has withstood the test of time. Whether it be referring to a person's age or an object's longevity, these synonyms provide alternative ways to express the idea of extreme old age.