Crowds are gathering in Istanbul for a massive rally to mark the end of nightly democracy demonstrations following Turkey's abortive July 15 coup that killed over 270 people.

Sunday's "Democracy and Martyrs' Rally" aims to represent Turkish unity, with President Recep Tayyip Erdogan urging attendees to bring only the Turkish flag instead of party banners. He says "there we will stand together as a single nation, a single flag, a single motherland, a single state, a single spirit."

The event will be attended by the highest levels of Turkish leadership and two of Turkey's three opposition parties. The pro-Kurdish People's Democracy Party, or HDP, was not invited.

Nearly 15,000 police will be providing security at the event, which the state-run Anadolu news agency estimates could be attended by millions.