Noted New England architect John Calvin Stevens designed the L. D. M. Sweat Memorial Galleries, which opened to the public in 1911.

Recognizing the museum's physical limitations, he also gave $8 million toward the building of an addition to be designed by Henry Nichols Cobb of I. M. Pei & Partners.

The major European movements from impressionism through surrealism are represented by the Joan Whitney Payson, Albert Otten, and Scott M. Black collections, which include works by Giambattista Pittoni, Mary Cassatt, Edgar Degas, René Magritte, Claude Monet, Edvard Munch, Pablo Picasso, and Auguste Rodin.

In January 2000, the museum launched a $13.5 million capital campaign to raise funds for the preservation and educational interpretation of its two historic structures.

The museum's expanded space allows a more complete presentation of the permanent collection, which in recent years has grown in quality and historical importance.

[4] The building at 142 Free Street was built in 1830 as a theatre, then served as a Baptist church for 85 years before being purchased by the Portland Chamber of Commerce in 1926 and being renovated by John Calvin Stevens.

"Our region is one that is striving to become more inclusive, dynamic, and diverse – a city where everyone belongs – and some architecture styles can carry unfortunate legacies of the past into the future that undermine these values and goals,” Bessire wrote.

[9] History professor KC Johnson called the argument a "cynical effort to exploit contemporary cultural mores to serve the Museum of Art’s short-term economic interests.

"[10] Museum board chair Elizabeth McCandless wrote that demolishing 142 Free Street "is essential for our neighborhood, our city and for all who reside in and visit this area" and acknowledged the proposal's "divisiveness within the community.