St. Martinville, in the 19th century, was a fashionable resort attracting affluent residents of New Orleans seeking a summertime escape from the heat and yellow fever of the city. It was also a place of refuge for French Royalists during and after the French Revolution. And what better place to show off their finery than in the Union Ballroom of the hotel believed to have been built by Jean Pierre Vasseur between 1835 and 1840.
During the Civil War, the building remained open to serve as a meeting place for community activities. Brother's Anton and Wilhelm Hesse operated the Maison des Allemands in the building from 1858 to 1876. From 1876 to 1899, Charles Gauthier, the Charles Gauthier Estate and Stanislas Dabadie owned the building in succession. During that time, Delia Greig Castillo, widow of Edmond Castillo, a well-known steamboat captain, operated the Castillo Hotel in the building. Although she never actually owned the hotel, she ran it extremely well, and it became known throughout the area for its fine hospitality.
In 1885, Castillo's granddaughter, Eva Bonin, married Alphonse Guerin, who was later appointed librarian for a subscription library established in the hotel. Guerin a native of France and a gourmet cook brought fame to the hotel for his banquets and dinners.
Castillo died in 1899, and the building was sold to the Sisters of Mercy to expand a school established in 1881. The nuns maintained the building, although they were unable to make major improvements. Climate and weather took a heavy toll. The Convent of Mercy School, then called Mercy High School, closed in 1986. The following year, Peggy Hulin bought the property.