Someone could say there is an “Area 51” situated in Fuerteventura, but in fact there is (apparently the Europe’s first) stratoport built.

It should serve for take off and landing of pseudo satelites and high altitude drones. The runway 02/20 is a bit more than 900m long (don’t know if including or excluding the displaced threshold.)

It is situated at the old Fuerteventura airport (Antiguo Aeropuerto de los Estancos, which I’ve visited back in 2020). At that time there was no mention of building this stratoport yet…

You can find the exact location of stratoport here: https://maps.app.goo.gl/ZaZqYLhBv6dvCmUs8