The Nathan and Mary (Polly) Johnson properties are a National Historic Landmark at 17–19 and 21 Seventh Street in New Bedford, Massachusetts.

[2] The two properties are significant for their association with leading members of the abolitionist movement in Massachusetts, and as the only surviving residence in New Bedford (out of three known) of Frederick Douglass.

The building's interior has woodwork dating to the early 19th century, including a staircase with elaborately turned newel posts.

This block appears to have been built in 1857, when Polly Johnson (in Nathan's absence) sought permission to move the original older house to the back of the lot.

[3] Nathan Johnson was born a free person of color in Philadelphia, and married Mary ("Polly") Durfee of New Bedford in 1819.

The couple were in the employ of Charles Waln Morgan, a prominent whaling captain, as domestic servants in the 1820s, and were soon involved in the abolitionist cause.

By 1845 the Johnsons had enough success in business that they owned the lot including these two buildings and an adjacent one (then numbered 23 Seventh Street, but no longer standing) which they used as a shop.