The Initiation Well is one of many interesting things to see and experience at the Quinta da Regaleir grounds.
This is a subterranean tower which sinks 27 meters into the hillside.
You can access the well from the bottom at the Portal of the Guardians entrance or through the connecting cave tunnels. There is another entrance at the topside.
This is the view from the topside.
The well is lined with stone walls and is large enough to support a spiral staircase which winds its way from top to bottom.