Learn about the scientists, inventors and entrepreneurs who made Cambridge and Boston two of the most innovative cities in America on a walking tour of the Innovation Trail. With dozens of sites spanning Boston’s Downtown Crossing to Cambridge’s Central Square, the Innovation Trail gives everyone the chance to experience, learn about and be inspired by four centuries of world-changing breakthroughs from Greater Boston. Think it’s just boring science? Think again. Destinations include Boston's first clinical trial, a response to a smallpox epidemic in the 1600s; the place where Thomas Edison launched his career as an inventor with a complete flop; where Alexander Graham Bell invented the telephone; how a company founded in a railroad car in Cambridge led to "The Wizard of Oz"; plus how a Boston entrepreneur introduced ice to gin-and-tonics around the world. The Innovation Trail shows a myriad of discoveries and advancements from a diverse group of men and women, how gaining independence as a nation after the Revolution was just the beginning. What happened in Boston after America became an independent nation is equally as astounding.