By the 1830s, the parish church of Mosta, which had been built in the 17th century by the architect Tommaso Dingli, had become too small to cater for the town's population. Grognet proposed rebuilding the church on a neoclassical design based on the Pantheon in Rome. Despite opposition from Bishop Francesco Saverio Caruana, the design was approved and construction of the church began on 30 May 1833. Grognet had never received any formal architectural training, so during construction he received consultation services from a member of the Sammut family. The church took 28 years to build, being completed in the early 1860s. The church's design was praised both during construction and after its completion, and it is considered to be Grognet's masterpiece.
