“Viewpoints” brings together some of the most enduring and powerful photographs of the 20th century, investigating photography’s transformative power and its role in contributing to collective memories. The exhibition celebrates photography both as an art form and as a social, cultural, and political force. Presenting 150 highlights from the Howard Greenberg Collection of Photographs—a group of 446 images recently acquired by the MFA—the exhibition showcases the collection’s breadth.