Higher education

I see that others have expressed interest in this issue: whether it is possible to achieve a teaching position at the university level in one's 50s? I am about to finish my Master's Degree in History of Design and Decorative Arts and would like to teach in a college/university setting. Do I need the PhD? Will I help or hurt my chances by pursuing it? Are there jobs out there for people of my age, or do universities only hire younger people?

Thanks for the insights!