Complex sentence: In fact, the Dumas operated legally as such from 1890 until 1982 and was the largest, grandest and most widely-known bordello among many located in Butte's thriving Red Light District.
Split into simpler sentences: In fact, The Dumas operated legally as such from 1890 all the way until 1982. The Dumas was the largest, grandest and perhaps best-known bordello among many located in Butte's previously thriving Red Light District.