Section 4: Gameplay
Why People Get This Wrong
People often think they can just skip buying unowned properties without consequence, which leads them to argue about whether they should auction these spaces at all or if it's even their responsibility to do so when no one else wants them. The confusion arises because this rule is not clearly explained in the standard Monopoly ruleset and some players might miss its importance during casual games.
Official Verdict
If you land on an unowned property and decline to buy it, it must be auctioned to the highest bidder, starting from any amount. This is in the published rules and is probably the most widely ignored rule in the game — skipping it is the main reason casual games run so long.