John Eliot Thayer (1862–1933) was an amateur ornithologist and member of the wealthy Thayer Family in Lancaster, Massachusetts. Due to his family’s business dealings, John Thayer was able to turn his passion, studying birds, into one of the largest collections of stuffed birds, eggs and nests for professionals all over the country to study. John began collecting and housed his collections were in several wooden buildings close to his home in Lancaster, but when these became unsafe and crowded he built this beautiful brick building in 1903 in South Lancaster opening it to the public as a museum a year later. The Boston architectural firm of Winslow & Bigelow designed the Colonial Revival style building, with the Guastavino Fireproof Construction Company providing plans for interior spaces and likely engineering inside. Many of the leading ornithologists of the time visited the Thayer Museum and it was estimated that more than ten thousand visitors came to the museum in the first six years.  In 1974, the building was sold to the now defunct Atlantic Union College and reopened as the Mabel Bartlett Art Gallery. Much of the Thayer collection was donated to the Museum of Comparative Zoology at Mr. Thayer’s alma mater, Harvard University. Since the Atlantic Union College closed in 2018, this important building has been closed, hopefully to see reuse in the eventual redevelopment of the campus.