In your attempt to hightail it to the Aventura Mall to get your Gap on, you may have unknowingly driven right past a true fashion treasure along Biscayne Boulevard. You won't find capris in C. Madeleine's -- unless they're from the Fifties, and they most certainly won't be khaki. A veteran on the vintage scene, owner Madeleine Kirsh pays exquisite detail to the items that go into her 10,000-square-foot boutique, which she opened four years ago. Its inventory arranged by decade, Madeleine's offers everything from Civil War military jackets (you gotta ask, because this kind of stuff is holed up in a back-room vault) to gowns admired by celeb fans such as Naomi Campbell. Although you may run into a few bargains, be prepared to pay for history -- this is, after all, a vintage store (not thrift) -- and it wouldn't be unusual to stumble upon a $60,000 mink coat. But then again, do you really need another pair of Old Navy gaucho pants?