The church is near the ruined city gate which shares its name, at the site of the old grain market. The main entrance to the city was here in the ninth century. What is most interesing about this church is that is was built on a terrace that is above a row of shops. Using bonds, the Genovese built these shops, so that the very expensive rent from them might help pay for the cost of building the church. It was built according to the plans of B. Cantone, G. Ponzello and il Vannone. Work was finished in the second half of the sixteenth century. Il Vannone was also the architect of the Loggia for the Merchants or the bankers. The church also was given the name "S.Maria Immacolata", thanking the Madonna for the end of a plague. In front of the church there is a beautiful flight of steps. The church itself has a central plan with a large octagonal cupola and four spires, one of which is missing. It is a copy of Church of Santa Maria Assunta in Carignano. The outside of the church is decorated with frescoes from the seventeenth century which have been recently restored. Inside, there are precious stuccoes and frescoes by M. Sparzo, A. Semino, A. Ansaldo and P.G. Piola.