In this question, I asked if it would be possible to make a city like Venice, but with lava instead of water. The answers I got showed that the city would be very impractical, due to toxic gases and other things.
But, is there anything that could replace the lava, so there are still hot streams of liquid below the city?
I have some guesses, such as boiling springs or molten metal, but I don't know what would be the safest. It does not need to be safe to fall into (I want it to be quite the oppisite actually), it just needs to be safe to live above.