Until recent decades, it was thought that the church of San Gian was originally built in its current form. However, excavations carried out by the archaeological service of Canton Graubünden in the year 1974 showed that a smaller chapel once stood on this site. The chapel occupied more or less the south side of today's church, but it seems it was not connected to the small tower. In 1478 Bishop Ortlieb von Brandis had the current church built, along with the large late-Gothic tower. In 1682, the tower's large wooden spire was struck by lightning, and completely destroyed. The church was restored between 1973 and 1980.