More than 3,000 police were deployed in and around the Holy City on Wednesday as Israelis marked Jerusalem Day to remember the city's reunification 44 years ago after the Six Day War in 1967.
"We have deployed extra police, border guards and civil guard volunteers, particularly in the eastern part of the city and in and around the Old City to maintain public order during the ceremonies," police spokesman Micky Rosenfeld told AFP.
The celebrations, which began at sundown on Tuesday and continued through the night, include parties, parades and ceremonies.
Security was tight throughout Jerusalem ahead of an annual march to the Western Wall in the Old City, one of Judaism's holiest sites.
Police said they were expecting up to 30,000 people to attend the parade, which normally heads down Jaffa Street, the main artery running from the city's western entrance to the walled Old City.
But this year, with a new light rail system running the length of Jaffa Street, the march has been rerouted and will take place almost entirely in the eastern sector, in a move which police fear may spark clashes.
Israel considers the entire city as its "eternal, indivisible capital."
"Jerusalem will never again be divided," Israeli Prime Minister Benjamin Netanyahu said during a ceremony to mark the occasion on Tuesday evening.