If the administration does not carry out the work or does not use the expropriated property for the purpose for which it was expropriated, you can exercise the right of reversion, which allows you to recover the expropriated property by returning the price received. This right must be exercised within the legally established term and is subject to certain conditions, but it constitutes an important protection against expropriations that finally do not materialize or that are used for purposes other than those declared.