Chester County is one of the three original counties formed in 1682 in southeastern Pennsylvania by William Penn under Charter signed by King Charles II. The greatest number of settlers after 1682 came from the British Isles, and so the architecture they created bears out their mostly British roots. This survey includes homes, barns, out buildings, and commercial properties built here from the county's 17th century beginnings through the 19th century. Thousands of original source documents were examined to build the text and factual lists contained here. Hundreds of overall and detail photographs and select plan drawings are included to illustrate a few of the buildings.