I'm not too technically knowledgable yet, but I would guess it was to do with the light and not being enough. You could up your iso and also open up your aperture to let light in.
Just had a look at your info and f11 is quite narrow. Try widening and see what you get. It is all practice and trials. Good luck! This is a nice silhouette though.
Thank you @wag864. The reason I kept the f quite narrow was in the attempt to obtain a silhouette instead of the clear image of the tower. Same with ISO. I will try again following your suggestions as soon as I go back to Verona. I really appreciate the help!
Caterina, to get the building silhouetted expose for the sky and the subject falls into shadow - that's my understanding - then you get your silhouette. The image is a little flat but it gives it a kinda oldie gothicy horror look, the tower looks quite sinister which I like :) Did you shoot raw or jpeg? If you shot raw you really need to edit the image to bring out the contrast and clarity, that should make the image pop. Also, play with the shadows and highlights to get the feel you're after. Upping your ISO will only add more noise, you need to shoot as low as you can go - 100/200. You was at 200 ISO so not sure why it looks so noisy. Hope this helps. I've learned over the last year photography is all about trial and error and just enjoying the moment :)
@paul10 I shoot both raw and JPEG but then I only use JPEG because I don't know how to PP, or better I don't have lightroom or Photoshop, because I'm afraid I don't have the time to learn how to use it. But your advice pushes me to try. I agree that ISO was low enough not to cause noise and from what I read Photoshop could help reduce it. But, as you say it's a matter of trial and error and the tower has been there for centuries, I trust I will have another occasion to take a picture! Thank you so much for your comment, I really appreciate any comment and/or criticism
@caterina I found a previous version of Photoshop too confusing. Lightroom is great for editing raw files and you can reduce noise in there too for a fraction of the cost. A raw file is basically an old fil negative. All the information is there in the raw file but it's all flattened. Just playing around with the sliders can make huge differences to the look and feel of the image where as with Jpeg what you see is what you've got. Honestly, I learn all my stuff from YouTube - I follow photography vloggers like Thomas Heaton and Paul G Johnson and Gavin Hoey. Learn loads from them :)
I was wondering why everybody said they were learning by being members of 365 project. Now I know. You are very helpful