Complex sentence: The administrative seat (formerly located in Ruwer, which was an independent municipality until it was incorporated into the city of Trier) has been located in Waldrach since November 2005.
Split into simpler sentences: The administrative seat used to be located in Ruwer, which was an independent municipality until it was incorporated into the city of Trier. The seat has been located in Waldrach since November 2005.