Complex sentence: Parliament has sat at Parliament House, Melbourne since 1856, with the exception of the period 1901--1927, when Parliament House was used by the Federal Parliament and the Parliament of Victoria sat at the Royal Exhibition Building.
Split into simpler sentences: Parliament has sat at Parliament House, Melbourne since that time, with the exception of the period 1901--1927. During that time Parliament House was used by the Federal Parliament and the Parliament of Victoria sat at the Royal Exhibition Building.