GALLERY 3 Founded in 1521, San Juan, Puerto Rico, is the oldest city flying the American Flag. In 1971, this historic capital was honored with an 8-cent stamp commemorating San Juan's 450th anniversary. VIEW CURRENT EXHIBIT PICTURE 3-1   PICTURE 3-2   PICTURE 3-3   PICTURE 3-4 PICTURE 3-5   PICTURE 3-6   PICTURE 3-7   PICTURE 3-8 PICTURE 3-9   PICTURE 3-10   PICTURE 3-11   PICTURE 3-12