515 North Washington Street | |
 515 North Washington Street in 2022 | |
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| Location | 515 North Washington Street Alexandria, Virginia |
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| Coordinates | 38°48′37.4″N 77°2′44.8″W / 38.810389°N 77.045778°W |
| Built | 1848 |
| Part of | Alexandria Historic District |
| Designated CP | November 13, 1966 |
The historic building located at 515 North Washington Street in Alexandria, Virginia, United States, has been used as a cotton mill, prison, factory, office space, and apartments. It was built by the Mount Vernon Manufacturing Company in 1848 in present-day Old Town Alexandria. After the original owners were unsuccessful with their cotton mill business venture, the building was sold in 1855. After a renovation, the new owner was able to operate a successful business, but his success was cut short after the Civil War began. The building was one of many local businesses that the Union Army seized after it entered Alexandria. After briefly serving as a hospital and warehouse, the mill was repurposed and renamed the Washington Street Military Prison, the largest of the five Civil War prisons in the city. Rufus Dudley Pettit was named warden in 1864 and he was responsible for widespread abuse and sadistic behavior towards prisoners.
After the war the building briefly reverted to operating as a cotton mill, but after that business venture failed, it was sold and sat empty until 1902 when Robert Portner and his Portner Brewing Company purchased the property. The building operated as a bottling plant until Virginia passed Prohibition legislation, resulting in the plant's closure. It was purchased by the Express Spark Plug Company which made spark plugs there until it went out of business in 1928. The building was converted into the Belle Haven Apartment House in the 1930s and it remained in residential use until 1981, when it was renovated and became office space. The building was the headquarters for the International Association of Chiefs of Police from 1992 until 2014, when the property once again underwent a renovation. Since the building is a contributing property to the Alexandria Historic District, the project underwent a review by historic preservation organizations. The property was converted into The Mill, a 25-unit apartment building featuring original architectural details and an adjoining park.
An interesting feature of the building is that a mannequin nicknamed Oscar is perched in the cupola. There are a few rumors as to Oscar's origin, but the most likely story is that it was brought into the building sometime around 1920. The other rumors are that it was placed there by local police after an employee was brutally murdered on the property in 1854 or that prison guards would use it as a stand-in when they would go on breaks. Oscar is treated as an historical part of the building and during the most recent renovation, it was carefully preserved.