The Lemptegy vulcano has been dig out since 1944. The light material that surrounds the dome seems to be ideal building material since it is so light and very well isolating. It is mainly used in road building.
When you don't see the puzzle, it is possible that we haven't uploaded it to our new puzzlehost yet.
Read here why the puzzles look different and which problems there can be
Unfortunately our old puzzle script stopped working and we have to move all 1800 puzzles elsewhere. We can only upload 99 imags to teh new host, so it can take a few weeks before they all work again, ou apologies.