Complex sentence: Plans for the grand hotel were conceived in 1900 by William C. Muschenheim and his brother, Frederick A. Muschenheim, when the area, then known as Longacre Square, stood beyond the fringe of metropolitan life, the center of New York's carriage-building trade.
Split into simpler sentences: Plans for the grand hotel were conceived in 1900 by William C. Muschenheim and his brother, Frederick A. Muschenheim. The area was then known as Longacre Square and stood beyond the fringe of metropolitan life, the center of New York's carriage-building trade.