Ask people to name the top Mexican food capitals north of the border, and Los Angeles will surely pop up first, followed by just about everywhere in Texas. Yet Chicago actually has the second-largest Mexican population of any city in the U.S. (second only to L.A.)— and that means we also have a remarkable array of Mexican restaurants in nearly every neighborhood in town. As our part of Grub Street's national series of taco slideshows, we're going to take you on a tour of Chicago's bountiful taco diversity, taking in everything from the north side to the south side to the west side, from Rick Bayless's artisanal Mexican food to hole-in-the-wall stands. Our tour will begin with some places you've heard a lot about, and with the ubiquitous basics of carne asada (steak) and pastor (marinated pork), but it will branch out into every neighborhood and every kind of taco filling you can imagine. We're sure there will be arguments as to whether these are truly the 25 best (and we're happy to hear alternative suggestions in the comments), but at least we can testify personally that you'll be very, very happy eating your way through this list and getting to know some of these spots in every corner of the city.