The house remains on its original site and has received minimal alteration. After the death of William R. Rodman in 1855, the house was purchased by Abraham Howland, New Bedford's first mayor. It became the political center of the city for two generations since Abraham Howland, Jr., also held the mayor's office. After his death in 1887, the mansion was owned briefly by members of the Grinnell and Howland families who wished to insure the safety of the house.

The next owner of the Rodman Mansion, mill executive, Joseph Knowles, in 1909 added a small south wing to the house and a rear annex. The project architect was Nat C. Smith. Knowles died soon after the wing was added and local physician, John Gael Hathaway lived at 388 County Street until his death in 1919.

Walter Hamer Langshaw, the last private owner of the Rodman Mansion, lived in the grand manner. A self-made millionaire, president of the Dartmouth Mills, Mr. Langshaw spent over $100,000 on a project that added Georgian Revival elements to the house. The Boston architectural firm of Little & Brown designed a South facade solarium, one of the most elegant and finely detailed in New Bedford. Major first and second floor rooms received elaborate Georgian plasterwork. A mosaic floor was laid in the entrance hall. Specially commissioned murals were painted for the music room and hall. Langshaw, an amateur musician, also closed in the Palladian window on the main staircase with an organ loft.

The Langshaw family remained in the house until 1950 when it was sold to the New Bedford Jewish Federation for use as a community center. In 1972, the Swain School of Design purchased the mansion. It was sold in 1988 to the William Rodman Partnership, which extensively renovated, and still owns it. That restoration won the 1990 Preservation Award from the Massachusetts Historical Commission.

By 1833 Russell Warren had designed the first of his great New Bedford buildings, the 1831 Joseph Grinnell Mansion on the west side of County Street across from Rodman's 1.72-acre site. Warren had also designed the Double Bank building on North Water Street. In 1833 he had two major city commissions, the Rodman Mansion and the massive John Avery Parker house.

In his design for the 47-year-old William R. Rodman, Warren emphasized the grace and elegance that the Greek Revival style was capable of achieving. The Grinnell Mansion had been a deliberately severe granite building intended to be a reminder of the importance Congressman Grinnell held in New Bedford. For the Rodman Mansion while again using granite as his principal building material, Warren designed the major front facade of the Mansion in smooth granite. A two story wooden portico with six fluted Corinthian columns dominates this facade. The house has five bays with six over six windows reaching almost floor to ceiling and filling the interior of the house with light. The remaining facades of the mansion were constructed using rough-hewn granite. Built in a U shape with projecting rear wings, the Rodman Mansion rose two and a half stories exclusive of the basement.

A 1909 Morning Mercury article described the original construction of the mansion. "It is of interest that the mansion was erected by a Providence contractor who afterwards came to make his home in this city, Augustus Greene was at that time a contractor and builder in Providence and he came to this city to build the house for William R. Rodman. The wooden columns in front of the house were then regarded as something very ornate as indeed they were. They were built in Providence and were shipped to this city in a sloop. They were unloaded at one of the wharves and carted to the house where they were placed in position."

The interior of the house retains all of the Georgian Revival additions made by Walter Langshaw and all of the Original black marble fireplaces designed by Warren. There are now twenty rooms with sixteen foot ceilings. Entering the house a visitor faces the double staircase at the rear of the entrance hall. Rooms are arranged to the left and right of the hall. On the immediate right are double parlors with marble mantels, which is used as one large lecture room. Behind the parlor is the former dining room, now the president's office. To the left of the hall is a small library now used as an office and Mr. Langshaw's music room.

The second floor contains four large master bedrooms with fine Georgian plasterwork, which are offices. An annex contains two smaller offices. The third floor has six rooms. Floors throughout are parquette, oak, ceramic and mosaic tile.