1. Money Belt
Having a money belt will be so helpful to bring here when traveling. This is where you can store the rest of your cash and extra things as well. Personally, I would not keep any important items in the money belt just in case.
2. Travel Power Converter
A travel power converter is a must need when you go anywhere in Europe. If you want a good one that you can use in the future I would suggest buying it off of Amazon. I would get one with two usb cords because so that way you will have more room.
3. Comfortable Shoes
Let me tell you, you will definitely need comfy walking shoes. Do not worry about looks comfort will matter the most. That was my biggest mistake.
4. Non-expensive sunglasses
It is your preference if you would like to bring your good pair or cheap ones. Personally, I would bring a less expensive pair. If you lose them you will not be as upset.
5. Go Pro or Selfie Stick
If you are traveling in a group, having a selfie stick or a go pro will be nice to have so you can take your own pictures. Having another option besides your phone will be useful. Especially, to have available if you need to take a quick picture.