In the essential structure it reminds one strongly of MONOPOLY. The author team Donadoni/da Vinci inserted another whole set of details which make LEONARDO its own game. At the beginning, each player secretly decides to which of the two groups of aristocracy (the Pope-faithful Guelfen and/or the emperor-faithful Ghibellinen) he would like to belong. On some spaces event cards are drawn, and those give one group or the other a financial boost.
There is a variant. It offers opportunity to the players to unite in guilds.