In the standard Monopoly board game, four houses can be built on one property before replacing them with a hotel.
A player must own every property in a color group before developing that group. Houses are then added according to the printed building cost, and the rules require buildings to be distributed evenly across the group. A property cannot receive a second house while another property in the same group has none.
After four houses stand on a property, the owner may exchange those four houses for a hotel, subject to the bank having the required hotel and the game’s building rules. A hotel is the highest standard development level for a property.
Some special editions use different pieces or rules, but four houses followed by a hotel is the classic standard progression. This rule is separate from the total number of houses supplied in the bank.