Tucked away in a nondescript Montrose strip center, next to indulgent sweets shops, Retro Gallery is easy to miss by day. At night, when owner Lyle Cohen gives a customer a by-appointment tour, the store's lights shine brilliantly on an exotic and vividly colored Italian poster of On the Waterfront; delightfully garish Japanese James Bond posters; and wall-size pre-World War II French advertising posters for wine, cars, soap, bicycles. It's a candy store for the eyes. Retro Gallery's walls hold all kinds of original advertising poster art, mostly imported, many from early in the 20th century. There are no reproductions. There are similar stores in New York or Chicago and an online market for such posters, but Retro Gallery is unique to this region.