You're welcome - good luck, have fun, and remember to respect the wishes of original model creators! (some are ok with re uploads, others are absolutely not)

Thanks for answering my question eventhough it wasn't all that understandable. Sound advice about the premission and credit, and the ModTools and re-import explains a lot of what I need to do to accomplish this.

I don't understand your question. This asset is already assembled as shown. If you're asking "is it hard to take buildings from the workshop and change their use in Cities Skylines for a different purpose" my answer is 1. ask permission from the person who originally uploaded the model and make sure to give them credit as the original model maker (I did not do a very good job of that above, giving credit only to BeardMonkey but not to geze who uploaded the market cart and to whoever uploaded the windmill). 2. you will need ModTools and need to know how to dump the mesh and textures so you can re-import the building as a different type of asset in Cities asset editor.

Is it hard to put together? I cannot find anything similar for a medieval style although there are some good assets for it. If you have any tips, they would be much appriciated.