Northrop Cottage was built in 1906 by Mrs. Charles Richardson Baker, a widow from Brooklyn, New York. Mrs. Baker originally called the house Villa Conselyea after a street in Brooklyn. She built the Queen Anne, shingle-style cottage so her grandchildren could escape a serious diphtheria epidemic in New York City. To get from New York to Castine, the family traveled by a steamship heavily laden with belongings and servants. The house subsequently became known locally as Northrop Cottage, the surname of one of Mrs. Baker's grandchildren.

From a long line of ministers, the Baker family was instrumental in constructing the beautiful Episcopal Church on historic Perkins Street. The collection of religious books in the living room are remnants of the family's commitment to religious training and teaching.

While strolling the property, visitors may discover a low stone wall painstakingly built by local stone masons that marks the border of the six acre estate. Also, an old spring-fed well, there long before Northrop Cottage was built, is located near Battle Avenue. Native Americans used to visit the spring for the water's medicinal properties. An apple orchard can be spotted in front of the carriage house.

Northrop Cottage features many interesting details from the early 1900s. Brass wall sconces, servants bells, converted gas lamps, butler's pantry, leaded glass windows, soapstone counter, marble sinks, built-in window seats, and exquisite moldings are examples of some of the articles. Other facts of interest include: The room sitting atop the roof, commonly referred to as the widow's watch, was actually a replica of a deckhouse from a riverboat of Mark Twain's era. Fire hoses were located in the second and third floor hallways. Hand pumps, then located in the basement, were used to supply water to the upper floors in the event a fire ignited. Two large cisterns were located in the basement to capture rainwater. The water was then pumped to a third cistern in the attic of the house where the rainwater serviced the family's water needs.
The third floor living room was originally a billiard room where gentlemen of the day gathered. The carriage house was built by local shipbuilders. Square dances were common events in the carriage house and the upper floor was used by the grandchildren as a stage in play performances.