The Lesley-Travers Mansion was listed on the National Register of Historic Places in 1973. Portions of the content on this web page were adapted from a copy of the original nomination document. 
The basic organizing element of the Lesley-Travers Mansion (also known as Deemer House, Travers House, and Lesley House) is a five-bay, center-entry structure, to which are joined several appendages and wings. From an entrance hall, access is possible to three major adjoining rooms and a hallway. The three-sectioned oak stairway provides communication to the second floor from the entry hall. The house is stacked room-on-room throughout, including the basement, which, once served as servants' quarters.
The Lesley-Travers Mansion was executed in a Gothic Revival vocabulary, with particular attention to the quality of detailing. The walls, laid in common bond brick with flush joints, were intended to receive paint. The door and window jambs are splayed, the entrance doors have arched heads, and the water table is beveled. The windows are framed by cast-iron sills and hood mouldings, and glazed with French cylinder glass. Sheathed in slate shingle, the roof is trimmed with tin gutters, ridges, and valleys. Interior details include plaster mouldings, ribs, bosses, and other ceiling ornamentation.
Construction details include stone foundation walls faced with brick, and brick interior walls throughout the structure. The structural members are of pine, with pine and oak surface paneling. The house is equipped with speaking tubes, servants' bells, and an alarm system. The central heating system was installed when the house was constructed, and the original gas fixtures remain.
In 1855, Dr. Allen Voorhees Lesley signed articles of agreement with Thomas Dixon and James M. Dixon, Baltimore architects, to draw plane for his mansion in New Castle, During the same period when Rhenish castles [castles along the Rhine River] were appearing on the banks of the Hudson River, Dr. Lesley applied the impressions gleaned from his extensive travels to the plans for his own home.
Dr. Lesley presented the Dixons with detailed specifications for the finishing work on the house. The builder was Augustin Van Kirk of Salem, New Jersey.
A native of Philadelphia, Dr. Lesley was born on Vine Street in June of 1822. The, son and grandson of cabinetmakers, he deviated from the family trade to take a medical degree at the University of Pennsylvania. Dr. Lesley's reputation as a surgeon was well-known: at an early date, he applied microscopy and techniques of anesthesia, to the treatment of disease.
The Lesley connection with Delaware apparently springs from the purchase of a farm, near Delaware City by Allen Lesley's father, the secretary-treasurer of the Chesapeake and Delaware Canal Company. Dr. Lesley lived on the farm, for a time after graduating from the University of Pennsylvania, but moved to New Castle after his marriage in 1844. As a state senator and speaker of the senate, Dr. Lesley held Democratic, pro-slavery views.
Between Dr. Lesley's death in 1881 and 1903, the house remained in the hands of a succession caretakers. Seldon S. Deemer, a New Castle steel manufacturer, purchased the house in 1903. He restored the house and added new plantings to the garden already full of foreign shrubs that had been brought to New Castle and successfully domesticated. However, Deemer sold much of the acreage surrounding the mansion. John Campbell, who bought the property in 1930 for a fraction of the price Deemer had paid, continued the sale of the land. The house itself deteriorated, acquiring the name "Campbell's Folly." The house has again been restored to accommodate both living quarters and the office of a weekly newspaper.
Papers in the possession of Mrs. Major M. Travers, Jr.
Biographical and Genealogical History of the State of Delaware. Chambersburg, Pennsylvania: J.M. Runk & Company, 1899.
Eckman, Jeannette, ed. New Castle on the Delaware. New Castle: The New Castle Historical Society.
"Deemer Mansion," Typescript. University of Delaware, Delaware Collection.