Complex sentence: Taylor's first professional race took place in front of an estimated 5,000 spectators on December 5,1895, when he competed in a handicap event on an indoor track at New York City's Madison Square Garden on the opening day of a multi-day event.
Split into simpler sentences: Taylor's first professional race took place in front of an estimated 5,000 spectators on December 5,1895. He competed in a handicap event on an indoor track at New York City's Madison Square Garden on the opening day of a multi-day event.