Complex sentence: The Great New York City Fire of 1845 started around 3 a.m. on Saturday, 19 July 1845 on the third story of a whale-oil store at 34 New Street in Manhattan.
Split into simpler sentences: The Great New York City Fire of 1845 broke out on July 19,1845. The fire started around 3 a.m. on Saturday, 19 July 1845 on the third story of a whale-oil store at 34 New Street in Manhattan.