Occasionally there are news about a major ore deposit for a specific commodity being found. Some of these recent discoveries are underground, and the "geophysics" aspect of their exploration is more important than the "geology" aspect.
This makes me wonder—are there any such known ore deposits that have been found under cities? Some examples might be "the largest gold deposit ever, under Buckingham Palace" or "diamond bearing kimberlite pipe under Central Park in New York".