It’s hard to imagine ever getting a handle on the rich and strange history of New York City, but this weekend you can dig a little deeper with architect David Grider. He’ll be giving a free talk at Green-Wood Cemetery about how one man named James Gregory and his LES-based iron foundry helped shape not only this city, but our nation. With contributions ranging from the USS Monitor to the bronze bell used at Coney Island’s original escapist fantasy Dreamland, you can delve into this Forgotten New York and see how it really only takes one person to change history. The talk will be followed by a trolley tour (advance reservation recommended, with a discount to Green-Wood Historic Fund Members) where Grider will show visitors related sites in Green-Wood, including the final resting place of Gregory himself.