Complex sentence: He was a railway president and a society figure who had given up his mansion at 299 Madison Avenue a short time earlier in order to be nearer the work he found most appealing, that of social projects.
Split into simpler sentences: He was a railway president and a society figure who had given up his mansion at 299 Madison Avenue a short time earlier. He did this in order to be nearer the work he found most appealing, that of social projects.