In order for a sparkling wine to be called Champagne, it must come from the Champagne region of France — which, lucky for you, is the next stop.
From Colmar, head west to Reims (between three and four hours by train or car) and tour the city's ancient cellars and even more ancient cathedral — for more than 1,000 years, French Kings were actually crowned at Notre-Dame de Reims. You can also pop down to Chalons-en-Champagne, known as the "sparkling Venice" of France, for another taste of Champagne and medieval architecture.