We drove quite a ways into Wadi Hanifa, which is 120 kilometers long and runs through the city of Riyadh. There were some large properties with houses in the beginning, but the further we went, the sparser civilization got, although there seemed to be a lot construction going on in the middle of nowhere.
This is a BBQ and picnic space, designed for privacy. There had to have been at least 50 of them at this point along the wadi, and they are pretty common here. These setups are used mainly in the evenings, when they're packed with locals.
Wadi Hanifa dam, posted earlier: