What is "wellheads"

Usage examples of "wellheads".

So many people were moving about in the great stone courtyard, in and out of the arcades from brilliant sun to brittle shadow, rubber-necking up at the long Renaissance facade of the eastward side, or the Baroque clock-tower under which she had entered, or climbing about the two enormous wellheads to find good places for taking photographs.

Not far away were other geothermal wellheads, their natural pressurized steam deflected into huge insulated pipes.