"And if a man sells a dwelling house in a walled city..."Leviticus 25:29.

Properties within a walled city in the Land of Israel [walled since the times of Joshua] can be redeemed (i.e. repurchased) by the seller for an entire year following the sale. If the seller did not redeem the property within that window of time, the sold property remains permanently in the property of the buyer—it does not revert to the seller during the Jubilee Year.