The Custom House Maritime Museum in Newburyport, Massachusetts, resides in a former United States customhouse. Built in 1835, Newburyport's previous customhouse on State Street had burned in the Great Fire of 1811. This greek revival structure was designed by architect Robert Mills, who also designed the US Treasury building and the Washington Monument. The granite used to build the customhouse was quarried in Cape Ann and brought by barge to Newburyport where local masons shaped the rock, and assembled the building according to Mills' plans.

The museum was founded by the Newburyport Maritime Society in the 1970s with the goal of preserving and interpreting this history. It features historical objects related to maritime, local, and customhouse history, and a rich collection of primary source documents from the seventeenth to twentieth centuries.