The hole in the concrete block could be:
• A drainage outlet for overflow from the water tank or basin.
• A pipe sleeve where water lines passed through the floor.
The metal rods might have supported:
• A platform for the tank.
• A frame for a basin or washstand.
• Or even a protective cage around plumbing elements.
From this video: 廢墟探險-長洲鬼屋
Date picture taken
unknown
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