Lighting is key. Your photographs were taken at a time when there was a very wide range of lighting, which makes it hard to get a proper exposure that also looks good. If you expose for the turrets, the sky is blown out. If you expose to get the sky nice and blue, half of the photo is a silhouette due to the shade. There are unattractive shadows all over the building in #4. The best way to get around this is either wait for an overcast cloudy day where the lighting is more diffused, and the sun doesn't cast so many shadows, or bring a tripod and bracket exposures to make an HDR.
I'm sure the buildings are cool in person, but the area just does not seem like it offers a good composition to capture the whole structure. For this reason I think your photography would have been more effective if you focused on the building in pieces. A slit for the archers, the old brick doorways, the stairs and the barred window.
If this is a spot that you really like, what you should do is look at your own photos and decide what you like and what you don't like, and go back and try over and over untill you feel like you have the best photos you can possibly make from that area. Different techniques, different angles, different times of day for the lighting, etc.