Complex sentence: The seventh Nazi Party Rally, held in Nuremberg from 10--16 September 1935, featured the first session of the "Reichstag" held at that city since 1543.
Split into simpler sentences: The seventh Nazi Party Rally was held in Nuremberg from 10--16 September 1935. The Party Rally of September 1935 had featured the first session of the "Reichstag" held at that city since 1543.