Development began in earnest in the mid-19th century. In 1870, the Redemptorist Fathers built a humble wooden mission church that was replaced by an impressive Roxbury puddingstone structure in 1876. In 1910, dual-spires were added that now dominate the skyline. The church was elevated to basilica in 1954 by Pope Pius XII and is one of less than 100 in the United States. Officially named Our Lady of Perpetual Help after the icon of the same name, it is uniformly referred to as "Mission Church", even by its own parishioners. Due to a sloping foundation of this landmark, the west cross tops its tower at ; the other spire is two feet shorter. The length of the church is also , presenting a perfect proportion.