dsoftware.king wroteyour best bet would be becoming a minister. I am sure you won't have anything to worry about when you get old.
Except maybe a bomb under your car!
If you ask me about retirement I'd say retire in another country. Lebanon is small, and not that cheap anymore. But I don't have any specific idea for you especially since many countries will require visas, etc, but there are ways around that if you want to buy a house (= invest) in their country.
If you want to go the conventional way, banks have retirement plans. I know at bank med, they tried to sell me something like this once, where you'd put aside a small amount of money every month, and then when you are old you get a fund for retiring. If you (sadly) pass away before being able to take advantage, relatives will.
But I think, if you can, investing in a flat (or something else) to rent out will provide a steady stream of income, that sounds like a good retirement plan to me!