If you're not from town, or if you are but haven't gotten to it yet, you MUST visit Portillo's. They have the best hot dogs on the planet! There's not a whole lot of atmosphere, save for some antique-y decorations, but the food is well worth it. The hot dogs come on steamed poppy seed buns, which are delicious. The fries are great and even better with cheese sauce. And the milkshakes and chocolate cake are fantastic! The location in Chicago hasn't ever been busy when I've been there, although the ones in the suburbs tend to be packed. Definitely a Chicago tradition!