Tens of thousands of people are gathering to attend a rally in the Gaza Strip to mark the 25th anniversary of the Palestinian Islamist group Hamas.
Hamas political leader Khaled Meshaal is due to address the crowd during his first ever visit to the territory.
Mr Meshaal's visit follows a ceasefire that ended days of violence between Israel and Hamas last month.
He is expected to unveil a future strategy for Hamas and talk of reconciliation with its rival, Fatah.
Hamas removed Fatah from Gaza by force in 2007 after winning elections there. Fatah governs parts of the West Bank.
'Made in Gaza'
The BBC's Yolande Knell in Gaza City says the event is intended to send a message that, after 25 years, Hamas is a force to be reckoned with.
It enjoys support in Gaza and feels it is gaining regional political influence after the Arab uprisings brought new Islamist governments to power, she adds.
People are now making their way to the mass rally to hear the speech by Mr Meshaal.
Our correspondent says it is expected to focus on key issues such as the strategy with Israel, the future leadership of Hamas and reconciliation with Fatah.
In 2011, Mr Meshaal and Palestinian Authority President Mahmoud Abbas - the Fatah leader - endorsed an Egyptian plan to reconcile the rival factions and our correspondent says there may be announcements of significant steps to move the process forward.
But she says it is unlikely such a rally will hear any signs of moderation in the strategy towards Israel.
The centrepiece of Saturday's rally in Gaza City is a huge replica of a type of rocket Hamas militants fired at Jerusalem and Tel Aviv in the conflict with Israel last month. It has Made in Gaza written on it.
Some 170 Palestinians and six Israelis were killed in the eight-day engagement and Hamas has presented Saturday's event as a victory rally.
Ahmed Shaheen, attending the rally with his children, told Reuters: "This is a day of victory. The presence of Khaled Meshaal is a sign of this victory."
Israel says its operation killed Hamas's military commander and significantly reduced the militants' stockpile of rockets.
Israel, the US and the EU consider Hamas a terrorist organisation.
In terms of the Hamas leadership, Mr Meshaal said in January he did not wish to stand again as political chief and the future make-up at the top remains unclear.
Mr Meshaal entered Gaza from Egypt at the Rafah border crossing on Friday, touching his head to the ground in celebration. The streets of Gaza City were decorated with Palestinian and Hamas flags.
Correspondents say he was clearly aware of the desire among Palestinians for an end to the divisions that have weakened their cause.
Standing in the ruins of a house destroyed in an Israeli air strike, he said: "With God's will... reconciliation will be achieved. National unity is at hand."
Apart from a brief visit to the West Bank in 1975, Mr Meshaal had not visited the Palestinian territories since his family left in 1967.
He survived an Israeli assassination attempt in Jordan in 1997 only after King Hussein demanded an antidote to poison used by Israeli agents.
An Israeli official told the BBC that no guarantees for Mr Meshaal's safety in Gaza had been requested and none had been given.