With the latest update, every guild that owns a guild province is now able to build their own castles, fortifications, and buildings. The update has also added two new castles for three castles of each type and two new guild provinces in order to let all nations have access to the new guild castle features. Since being able to freely build a guild castle is such a drastic change, all existing guild castle fortifications had to be wiped out. However, players will have a few days to build their castles safely without being attacked.
Content retrieved from: https://massivelyop.com/2019/10/29/gloria-victis-brings-freebuilding-to-guild-castles-in-the-latest-update/.