The oldest building on Salem's campus is the Single Sisters' House. Originally constructed in 1785, an addition was added in 1819. The Single Sisters' House is the oldest building in the United States dedicated to the education of women. Renovation on the Single Sisters' House began in October 2005, and was completed for a re-opening ceremony on April 22, 2007 - marking the 235th anniversary of the founding of Salem. In the fourth-floor attic of the Single Sister's House is its original 1785 datestone. Several interesting features were found in the renovation process including graffiti that was covered by plaster. The building is featured in the children's book "Sister Maus," written and illustrated by Salem College Professor John Hutton. The story portrays a mouse as a stowaway on the trip from Bethlehem, Pennsylvania, to living in the Single Sisters' House. The story was inspired by a mouse hole found in a baseboard of the foyer.