France's government is deploying nearly 100,000 police and soldiers for the holiday season as fears of extremist attacks remain high.
Saudi Arabia's King Salman reportedly spent $100m (£77m) on his annual summer holiday to Morocco.
Iraqi forces opened exit routes for hundreds of civilians to flee the Old City of Mosul on Saturday as they battled to retake the ancient quarter from ISIS militants mounting a last stand in what was the de facto capital of their "caliphate".
The State Department issued a world-wide travel alert following a month of deadly terrorist attacks on three continents that have killed hundreds of people, including Americans.
Muslims in numerous countries celebrated Eid al-Fitr, marking the end of the holy month of Ramadan, on Thursday while other nations will observe the joyous occasion on Friday.