The Chicago River has a bad reputation for its polluted past, but the city has taken great strides to clean it up. They've also done a lot of work to make the riverwalk an appealing destination, and it's one of my favorite spots downtown. I especially love hanging out in the park near State Street, where you can sit and look up at the Trump Tower. Hang out here long enough and you'll see skateboarders, parkour practitioners, and maybe a bridal party getting photographed.