Maranatha Baptist University opened in Watertown in 1968, but its grounds had long been a school. Old Main, as it is known, with its distinctive cross-topped facade, dates to the 19th century, when the building first served the University of Our Lady of the Sacred Cross.
In 1871, the Congregation of Holy Cross at Notre Dame in Indiana purchased 65 acres in Watertown, and within a year, established a school with 27 students. Within a semester, 66 students had enrolled, and construction of a larger, main building was approved.
The "Watertown Gazette" reported that “On Wednesday, June 16th, 1873, the corner stone (sic) was laid with the usual solemnity of the Catholic ceremonial. At ten o'clock in the forenoon, the Rev. Father Corby assisted by several clergymen in sacerdotal robes, blessed the stone, and placed it at the northeast corner of the foundation.”
A contemporaneous advertisement read, “The College offers to students every facility for the attainment of a complete Classical, scientific and commercial education.” Board and tuition cost $100 every five months, and it cost an extra $5 to rent a bed and bedding.
After 1912, however, the school housed postulants looking to join the Brothers of Holy Cross, and in 1955, it was converted into a military boarding school.
The "Watertown Daily Times" reported that “The general purpose of education at Sacred Heart Military Academy is to train boys to become, under the inspiration of divine grace and the orderly pursuit of intellectual and moral truth, true Christian gentlemen.” The last 35 students graduated eighth grade in 1968, when the campus was purchased by Maranatha Baptist Bible College.