The city of Leon used to be located 20 miles east of the current city, but was abandoned due to a series of earthquakes. It has also been a rival city of Granada for a long time, and both competed as the capital of Nicaragua until Managua became the capital in 1852. The Spanish influence is very prominent here and there are several ornate churches, including one that you can climb on-top of in the center of the city.
I stayed in two different hostels while in Leon. Bigfoot is notorious for volcano boarding, partying, and meeting people, though I've been told that if you go volcano boarding with Quetzal Trekkers, a non-profit organization, you can go down twice for the same price. The second hostel that I stayed at was Tortuga Booluda, this hostel is further from the center of town and so you need to walk a little more to get to things. However, the hostal has a really chilled vibe and is great for making a more personal connection with people or just to spend time alone.
Overall I think that this was my favorite city in Nica. The people are friendly, it's not over-crowded anywhere, and you can find anything you need within a relatively short walk.