[mitthrowaway2]

One of the difficulties with this is the question of how you tax an asset whose value you don't necessarily know for certain, because real estate is not fungible and its market price is only really known when that specific parcel is changing hands between unaffiliated parties. Perhaps you could apply the tax as a lien, set as a percentage of an unknown value, and deferred until it is next sold, and have the government take back ownership of the land if that percentage reaches 100%. But even this might only encourage people to trade land between agents at suppressed prices, just to pay off the tax, and then flip it at its "real" price shortly thereafter.

[verall]

Every local government in America has basically figured out how to value real estate for taxation, although it's not perfect - I think that loans against a property should be limited to it's tax value as a first step, and ultimately land-value rather than improvement value should be taxed based on who else is trying to purchase the land.