Complex sentence: This was less than 2 years after the Philadelphia Nativist Riots, which represented the height of Anti-Catholicism and Know-Nothingism in Philadelphia and, according to local lore, greatly influenced the design of the building.
Split into simpler sentences: This was less than 2 years after the Philadelphia Nativist Riots. These riots represented the height of Anti-Catholicism and Know-Nothingism in Philadelphia and, according to local lore, greatly influenced the design of the building.