In 1854, the Portland Society for Natural History rented rooms in Portland’s Old City Hall, the museum’s second location. Built in 1825, Portlanders also called the building Old Market House and Old Town Hall, depending on the era.

Within five years, donors added natural history specimens including shells, minerals, birds, insects, fossils, plants, animal skulls, and eggs to the PSNH. The library also was replenished. Of note was poet Henry Wadsworth Longfellow’s donation in 1857, a commissioned copy portrait of naturalist Alexander von Humboldt.