Heave rain causes part of French castle to collapse Heavy rain in Brittany in recent weeks has left ground unstable and led to the collapse of the wall of the castle of Rohan in Pontivy. The castle was built at the end of the XVth century and beginning of the XVIth centuries. On Friday, around 4pm, part of the south wall collapsed bringing down part of the southwest tower to the great chagrin of local residents Images and soundbites.