Castle Expansions

Expansions are the plots of land in your castle that are used to build your buildings on. After the first two, they are unlocked in sets of 4 plots, either in a 2x2 or 2x 1x2 layout, take 8 hours to unlock and get progressively more expensive: Unlocking time can be skipped at the cost of 1 gem per hour remaining. You can't unlock more than 1 Expansion in parallel. .
 * third to last: 500 thousand gold
 * second to last: 1 million(?) gold
 * last: 2 million(?) gold
 * third to last: 500 thousand gold
 * second to last: 1 million(?) gold
 * last: 2 million(?) gold
 * second to last: 1 million(?) gold
 * last: 2 million(?) gold