Beacon Hill

This guide to Beacon Hill in Boston traces a shipment of English window glass installed in the neighborhood's new brick townhouses between 1818 and 1824, which left the factory perfectly clear and then began changing color in the sun. You'll hear about the manganese oxide behind the shift, the wealthy homeowners who were less than pleased, and how a flaw the manufacturer rushed to correct later became a point of pride for old Beacon Hill families. Look for surviving panes along Beacon and Chestnut streets, tucked among ordinary clear glass.