It is against the law for a man to make eye contact with a woman and when talking to another man, his wife or female children should not be brought up for discussion. Restaurants and even fast food places will have a family side and a male side. It is imperative that females utilize the family side of these establishments. If a woman is beign escorted by a man, usually the case, it is permissible for him to enter the family side with her.
During Prayer time (held 5 times a day) everything generaly shuts down. If you are in a shop you cannot pay for items until it is over (usually 20 minutes). You cannot get into establishments during prayer time either. Prayer times are posted in most papers so be prepared when planning shopping trips or evenings out.
Saudi Arabia is a completely dry country. It is illegal to bring alcohol to the country. So, make sure you don't do so. This also means that you will be unable to find any sort of alcohol anywhere in Riyadh.
Signs can be different from those in Europe. Luckily there's almost always an English translation or a helpful person around!
This dress for modern women, where only in big events it's seen. It may cost SR100-SR5000.
Also commonly seen in weddings and dance shows.