The Walker Art Gallery has a stunning collection of paintings from the 13th century to the present, it also has a sculpture gallery, a craft and design gallery, and a space specially designed for children which makes this an excellent day out for the whole family as well as the budding artist. What could make this better, you ask? It's free.
Now, if you're into art, this place has some fantastic pieces, from the old masters to 20th Century works. Check this place out even if you're not all that big into art..