The castle is the main touristic spot of Ancenis and it is an interesting castle to see. Parts of the castle have been built at different times, the first one being from the 16th century, the newest from the 19th. The castle stands near from the Loire raves.
Route d' Angers
Landed there when I was looking for a place where they would sell sandwiches and was really satisfied of le Bar de la Poste. Sandwiches are good and the prices are really reasonable: 3€ for a sandwich, 2.20€ for a beer.
A good thing to notice is that you have a connection to Internet in the bar.
There are around 15-20 trains a day from Nantes to Ancenis and they are pretty cheap: around 12-15€ for a go and come back. Note that most of the trains travel during the morning or after 5pm.