Signs and manmade tunnels

[JohnWick]

Hello guys, Im from Philippines and we just discovered in our farm the unfamilliar man made statue in the center of a vast land and a man made small river that has its hole and there is also a tunnel.
Can someone tell me whats the meaning of the sign?

 

[A2coins]

I cant help but that's cool Have you gone in the tunnel I'm thinking a possible grave place

 

[JohnWick]

Some local treasure hunter says it contains gold inside or beneath that statue

 

[A2coins]

That statue would be moved so quick all you would see is skid marks and his hair blown back lol