Colby House - New Castle, Delaware - American Guide Series on Waymarking.com

The COLBY HOUSE, 110 Delaware St., restored by Miss Ruth Colby in 1936, is one of the typical New Castle houses incorporating into the structure a seventeenth century dwelling.  In the back wing the ceiling rafters are heavy beams of oak covered with boards.  Whitewash of so many layers that it resembled plaster was found on the boards when the ceiling was cut through in remodeling.  The front section of the house was built in the early 1700's.  Its unspoiled main features, the belt course three bricks deep, the denticulated band adorning the cornice, and its excellent proportions make this one of the most charming small houses in New Castle. - Delaware - A Guide to the First State, New Castle section, 1938, pg. 248

The house at 110 Delaware Street is historically known as the "Rosemont House" and was built circa 1704.  The house is much as described in the Guide.  It appears to be very well maintained and is a contributing building in the New Castle Historic District.