About 1834, Évariste Blanc had this Greek Revival mansion built on his Bayou St. John estate. His widow, Marie Fannie Labatut Blanc, planned to give the property to the Archdiocese of New Orleans for a parish church as early as 1855 .Fifty years later, in fulfillment of her mother's wishes, Sylvanie Blanc Denegre donated the family home for the establishment of Our Lady of the Rosary Parish. When a temporary church was built in 1907, the Blanc mansion became the parish rectory, a function it has continued to fulfill ever since. The parish church, facing Esplanade Avenue, was dedicated in 1925, during the tenure of the founding pastor, Fr. William J. Vincent, 1907-1934.