A Michelangelo’s Script is needed to upgrade a building to level 10.

When you start off you have 1 Michelangelo’s Script. You can get more from special packages and promotions, you can buy them in the shop for 50 game cents (about $5 USD), you can win them off the wheel of fortune, and in a rare occasion you can get one from taking over a level 10 barbarian city.