The Astroturfing of Venice

So, we just finished a three week trip to Italy. That's what you do when you retire. You travel to places you've dreamed about, only to find out the gondola ride is vaguely reminiscent of the "Pirates of the Caribbean" ride you took at Disney World.

Then there are the true mysteries of life in an exotic culture. We were staying in an airbnb flat just a couple blocks from the Grand Canal. Very nice, great location, but there was a lot of construction going on in the area. One day we woke up to find workers nailing astroturf to the side of a building (see photo below). This led to endless speculation about why . . . my best theory was lack of dog parks and creation of a "doggy defecation" station at the corner where two lanes intersect.

Can anyone tell me why, oh why, would anyone put astroturf on the side of a building this way?