A Columbus Day tradition, the Fenway Alliance’s 17th annual Opening Our Doors celebration once again features gratis entry to such neighborhood institutions as the Isabella Stewart Gardner Museum, Museum of Fine Arts and The Mary Baker Eddy Library (pictured), as well as a slew of special events, including the free Pipes on the Plaza concert at the Extension of The Mother Church on Christian Science Plaza from 2–2:30 p.m., which is performed on one of the largest pipe organs of its kind in the world. Tours, dance and other opportunities to experience live music and visual art fill out a full day of entertainment in one of the city’s most culture-rich districts.