Land, do you own it all?

we don't really "own" a particular land. Wonder why we're paying taxes?

Depends on the law of the country you live in. But generally, if you can prove that something was found underground (no matter how deep) below land you own... like diamonds, it's yours. Try diggin past a kilometer though!

When you 'own' land it depends. The ownership rights are broken up into 'surface' rights and 'sub-surface' rights. The owner of the sub-surface rights depend on the legal rights granted by the state since ownership of land is regulated by the government. By the way, if you can lose your property for 'failure to pay taxes' then you do not own the land.