The Catherine Ahern Three-Decker is a historic triple decker at 215 Cambridge Street in Worcester, Massachusetts. It is a well-preserved example of a triple-decker that predates the popularity of that building type. Built in 1888, it has Italianate design details, including a low pitch hipped roof, and a decorated porch sheltering the front door. It is unusual in that its long side faces the street. Its first documented owner was Catherine Ahern. The building was listed on the National Register of Historic Places in 1990.