Complex sentence: He established his headquarters on the 18th floor of 270 Broadway in New York City, with the innocuous name of the Manhattan Engineer District, following the usual practice of naming engineer districts after the city in which its headquarters was located.
Split into simpler sentences: He established his headquarters on the 18th floor of 270 Broadway in New York City. It was given the innocuous name of the Manhattan Engineer District, following the usual practice of naming engineer districts after the city in which its headquarters was located.