Last Updated Apr 24, 2015 4:02 PM EDT
BEIRUT -- Around the world on Friday, tens of thousands of people of Armenian descent commemorated the genocide 100 years ago of 1.5 million Armenians by Ottoman Turks.
The annual April 24 commemorations mark the day when the mass killings started. An estimated 1.5 million died in massacres, deportations and forced marches that began in 1915 as Ottoman officials worried that the Christian Armenians would side with Russia, its enemy in World War I.
The event is widely viewed by historians as genocide. Turkey denies the deaths constituted genocide, saying the toll has been inflated and that those killed were victims of civil war and unrest.
During a 2010 interview with 60 Minutes correspondent Bob Simon, Turkey's then-ambassador, Nabi Sensoy, denied that death marches or massacres had occurred, and had this to say about the discovery of human remains: "Bones you can find anywhere in Turkey. There have been a lot of tragedies that happened in those lands."
Earlier this month, Pope Francis called the slaughter "the first genocide of the 20th century" and urged the international community to recognize it as such, sparking a diplomatic rift with Turkey at a delicate time in Christian-Muslim relations.
Here is a look at how the killings are being commemorated around the world.
Tens of thousands of Lebanese of Armenian descent marched the stretch of several miles from an Armenian church in northern Beirut to a soccer field where the commemoration service took place. Many waved Armenian and Lebanese flags and wore caps with "I remember and I demand" printed on them in Arabic.
Lebanon has one of the largest Armenian communities in the world outside Armenia itself - mostly descendants of people who fled their homes in 1915. Experts estimate the community to number about 150,000 people today, or 4 percent of the country's population. All public schools and some private schools closed on Friday to mark the occasion
Among those attending the Beirut service was Agop Djizmedjian, a 52-year-old supermarket employee who brought his 5-year-old son George.
"I brought George today to tell him that our ancestors were killed in this genocide," Djizmedjian said. "When I die, my son will teach his children until we get our rights."
In Beirut's predominantly Armenian district of Burj Hammoud, most of the shops were closed and balconies were decorated with the red, blue and orange Armenian flag.
Hagop Pakradounian, a Lebanese politician of Armenian descent, told a large number of people who gathered at the Beirut soccer stadium that Turkey should recognize its responsibility for the genocide since it inherited the Ottoman empire, adding that Ankara should "morally and financially" compensate Armenians.
Armenians in Lebanon hold six seats in the 128-member parliament, have three daily newspapers, several schools and one university.
Alex Martirian, a 64-year-old retiree, said "Turkey should recognize the genocide the way Germany recognized the Holocaust."
In Jerusalem's Old City, Armenian priests held a mass at St. James Cathedral, their chants rising to the sky in the cavernous centuries-old church adorned with hundreds of metal lamps as light filtered from the dome windows.
Dozens of Armenian community members from Jerusalem and Israel, Israeli Jews and others took part in the commemoration. Hundreds more waited outside the church and members of the Armenian community sold commemorative pins for the occasion.
Outside the church, gruesome black and white photos of decapitated heads and lynchings were framed in posters, along with slogans demanding justice. "Denial of murders is a crime. Turkey guilty of Armenian genocide" and "Armenians demand justice" read some of the signs.
After the two-hour mass, Armenian priests laid wreaths at a monument in front of the cathedral.
"We think and we understand that denying the genocide is the continuation of the genocide," said Inon Zalcman, a member of "The Combat Genocide Association." He added that "more than that, denial of genocide, one genocide is the opening gate for another genocide."
Rabbi Lee Bycel from California said he came to show his support for the Armenian people who died in a genocide that much of the world doesn't recognize. "I think both Israeli Jews and American Jews care a lot and support the Armenian people, but the governments are reluctant to acknowledge it."
Hundreds of Armenian-Iranians rallied outside the Turkish Embassy in downtown Tehran on Friday. Many chanted, "Death to the fascist government of Turkey."
The rally started with a march from an Armenian church in Tehran and ended peacefully around noon after the gathering outside the embassy.
President Joachim Gauck described the killings as genocide at a nondenominational service in Berlin on Thursday, organized by Germany's main churches - marking a shift in the country's stance after officials had previously avoided the term.
On Friday, the German parliament debated a non-binding motion that says "the fate of the Armenians is exemplary for the history of mass destruction, ethnic cleansing, expulsions and genocides which marks the 20th century in such a terrible way." Lawmakers are expected to approve a version of the motion in the coming weeks. Speaker Norbert Lammert, a member of Chancellor Angela Merkel's party, said Germany's own Nazi past makes it important to speak out on the issue. "We Germans cannot lecture anyone about dealing with their past, but we can through our own experiences encourage others to confront their history, even when it hurts," he said.
In Moscow, several thousand people gathered at the Armenian Apostolic Church complex for services in memory of the victims and the unveiling of a marble monument. White doves were released into the skies.
The church complex in Moscow is the largest Armenian religious facility outside Armenia itself.
In Paris, the Eiffel Tower went black at 2200 CET (2100 GMT). The sparkling lights will remain off for the whole night to commemorate the occasion.
On Thursday hundreds of people gathered on Paris' Place de la Republique square for a commemoration ceremony.
In Syria, several masses were held to commemorate the genocide in the capital Damascus, the northern city of Aleppo and the northwestern city of Hassakeh. In Damascus, Father Hai Ari Tnascian said the Armenian people were subjected to a racist genocide by the Ottomans in an attempt to eliminate the Armenian people and erase their historical, cultural and national heritage, state News Agency SANA reported.
Thousands of people marched in Los Angeles to commemorate the 100th anniversary of the killings. Many joined a six-mile walk from the Little Armenia neighborhood to the Turkish Consulate, carrying flags and signs.
The event comes after President Barack Obama once again stopped short of calling the 1915 killings a genocide.