Here are three photos of the church in Saint-Aignan, including one of the front and one of the back. The town's main street runs behind the church, so along with the church's profile on the town's skyline, this is the view of it you are likely to see first.
I say these are three photos because the second one (below) is an enlarged crop of the first. I thought the couple passing by the church was too picturesque to pass up. They were coming back from doing their market shopping and didn't appear to notice me taking the photo.
The front of the church faces away from the old town and toward the château instead. It's a massive pile of rocks, as you can see. This "soaring tower is a 19th century addition to the large Romanesque building beyond," says the Cadogan Loire guidebook.
The interior of the church was also radically "restored" in the 19th century. The most interesting part of the building is the crypt, where there are wall paintings from the 12th to 15th centuries (photos here).
The older parts of the church date back to the 11th and 12th centuries. Above is the view of the church's other enormous tower as seen from a little street just off the market square.