I have just moved and want to put a cast iron fireplace downstairs and up. Ive just scraped the paper away upstairs and found the fireplace concreted up. Should I leave it, have a go at knocking it through, get a builder in or what? any advice?

If you intend using the fireplaces then get a builder in to inspect them.

It's possible that they may have blocked the flu as well. Also, even if the flu isn't blocked deliberatly it may require repair and rennovtion before use.

Joe