Buildings by age in four Spanish cities. Madrid, Las Palmas, Barcelona and Valladolid

The aging of cities, that is, the recognition of their morphology, and not that of the populations that inhabit them, (which is also an extremely interesting aspect to know the vitality of a city) changes according to many factors, such as when it was founded the city, how quickly it grown, when it was renovation, destruction or maintenance shown by its buildings. Knowing the aging of a city is not always easy.

Today's merchandising processes have been creating in every city registration structures that are increasingly accurate, marking property data, property value, size, year of construction, year of ownership transfer, interventions ... Each country has been creating its own registry and if did not  (as in many countries of the old Iron Curtain), problems have arisen to identify owners, maintenance responsibilities, duties and charges.

One of the most developed tools for understanding our cities is the QGIS system. It is a Free and Open Source Geographic Information System.

In the Spanish case some computer tools available for free and relatively easy access help this system to generate interesting maps like the ones presented today, developed by Daniskarma, a Reddit user who has shared his work in r/DataIsBeautiful.

As explained in its Daniskarma entry, the QGIS has a plug-in called Spanish Inspire Catastral Downloader that allows you to choose a province and automatically download the data, drawing maps that help us in the knowledge of your analysis and diagno- sis before you start intervening in them.

Here, we leave your explanation and links that are quite illustrative:

Of course, for theses maps I used a shortcut. QGIS has a plugin named Spanish Inspire Catastral Downloader that let you choose a province and automatically download the data. In the building layer you have a field named "end" which is the end of construction date.

If you want to make a manual donwload, you'll have to go to the catastro main page https://www.sedecatastro.gob.es/ and select: "Descarga de datos y cartografía por municipio", then you have to donwload the shapefiles and the CAT files (which contain the age of construction data). But a electronic certificate is needed in order to download this data (It's free to make but it takes some paperwork to get one). I prefer to use the QGIS plugin.

All of this work for all Spain but Navarra and Euskadi, both of them have their own Catastro system. Althought the process is quite similar.