Complex sentence: Between 1921 and 1925 Ahrends built a new unostentatious cottage for his family which was located at Großer Wannsee on the estate of his father, close to "Villa Arons".
Split into simpler sentences: Between 1921 and 1925 Ahrends built a new unostentatious cottage for his family. It was located at Großer Wannsee, on the estate of his father, close to "Villa Arons".