The municipality of Madrid has slightly over 600 sq km, similar to the island of Menorca. But this size is the result of annexations, the last one being in 1960.
These annexations have allowed a uniformity in the way the structural systems are conceived, and especially the streets grid, which are not always present in metropolitan areas (for instance, in London or Paris such an area would be cut out among a myriad of municipalities), even if Madrid is today way larger than its municipality. This has allowed also an urban growth policy under a somehow homogeneous regulation: the result has been a relevant growth which, under a context of stagnant birth rates and reversed demographic glows, means a growing percentage of empty homes, which includes the sizeable amount of recently built homes.
The existing city renews, on the other hand, quite slowly.