We just sold a flat with a big copper worktop/splashback/surround @ILb
Pics here if you scroll down a bit:
You can only get sheets of copper up to a certain length in the UK (2m IIRC) so our builder ordered longer sheets from Germany to Poland where they were shaped, then he drove to Poland in his van to pick them up because he didn't trust anyone to ship them without damaging them.
Not sure if this is what you mean by 'aged' but ours was uncoated and the patina developed quickly with use. It was great and ever changing because water made it darker, lemon juice, ketchup, vinegar etc. lighter. Easy to clean too, just wipe down basically. It's naturally antibacterial, which is a bonus.
Would do it again in a shot but won't be able to get pieces that long (builder now specialises in microcement and polished concrete plus we couldn't afford it), our new kitchen would be at least as big and joins would bother me...
Bare in mind that copper is hard to glue down. Our builder managed it on the second go ;)