Walking into Union Station is a warm, inviting, humming way to enter the city of Denver. I pushed through the doors and stepped into a loud, crowded, busy scene of people waiting, working, talking, eating and drinking in a massive open space. Meet the authors Rich Grant and Irene Rawlings, authors of “100 Things to Do in Denver Before You Die,” will be at a book signing at the North Pole Marketplace following the Christmas Parade in downtown Golden on Dec.