Complex sentence: The commissioners published their plan in March 1811 in the form of an eight-foot map with 12 main north-south avenues and numerous cross streets, with Broadway running at an angle through it.
Split into simpler sentences: The commissioners published their plan in March 1811 in the form of an eight-foot map. The grid had 12 main north-south avenues and numerous cross streets, with Broadway running at an angle through it.