Muslim pilgrims make their way down on a rocky hill known as Mountain of Mercy, on the Plain of Arafat on Saturday.

More than 2 million pilgrims were gathered in the holy city of Makkah in Saudi Arabia on Friday to perform initial rites of the Hajj, an Islamic pilgrimage that takes the faithful along a path traversed by the Prophet Muhammad (PBUH) some 1,400 years ago.

On Friday, thousands of pilgrims circled the cube-shaped Kaaba in Makkah, Islam's holiest site. They circle the Kaaba counter-clockwise, their hearts tilting toward the structure that's meant to symbolise the monotheistic principle of the oneness of God in Islam. Muslims around the world pray toward the Kaaba daily, using compasses to help them pray in its direction.

Muslim pilgrims gather around the Kaaba.

Saudi King Salman invited as his guests to the Hajj this year 200 survivors and relatives of victims of a shooting spree in Christchurch, New Zealand, where a white gunman opened fire and killed 51 people in two mosques.

Those on the Hajj view the pilgrimage as an opportunity to strengthen one's faith, erase past sins and start anew. The Hajj is one of the five pillars of Islam, required of all Muslims to perform once in their lifetime if they are physically and financially able.

“All of the arms of state have been deployed (and) we are proud to serve as ‘God’s hosts’,” said security forces spokesman Bassam Attia.

"I am very happy now. It is the first time I am here in Makkah. I am very excited," Siti Haslina Yousof, a Malaysian pilgrim in Mecca, said.

The US consulate in Jiddah, Saudi Arabia said some 20,000 US citizens and residents were expected to take part in this year's Hajj.

"I cannot express my feelings. The atmosphere is spiritual, still and tranquil. We hope Yemen will be united for good," said Ali Ahmed Al Sudani, a Yemeni pilgrim who said he was praying for unity in his war-torn country. In total some 2.5 million faithful, the majority from abroad, will undertake the pilgrimage this year, according to local media.

“More than 1.8 million visas were delivered online without the need for middlemen. It’s a success,” said Hajj ministry official Hatim Bin Hassan Qadi.

Muslim pilgrims perform morning prayers at the Grand Mosque.

“We feel cleansed by achieving this pillar of Islam and meeting people from across the world. It’s marvellous,” said Mohamed Jaafar, a 40-year-old Egyptian pilgrim.

An indescribable feeling

“It’s an indescribable feeling. You have to live it to understand it,” said an Algerian in his fifties completing the pilgrimage for the first time.

“It’s a golden opportunity and moment,” said his female companion.

Muslims are doing Tawaf around the Kaaba.

Makkah, built in a desert valley, is home to the Kaaba, a cube structure that is the focal point of Islam and draped in a gold-embroidered black cloth.

Muslims around the world pray towards the Kaaba, which is located in the Grand Mosque, and pilgrims walk around it seven times.

Muslims pray at the Grand Mosque during the annual Hajj pilgrimage.

During the pilgrimage separate streams of men and women, grouped by nationality, will travel to Mina on foot or in buses provided by the authorities.

A district of Makkah, Mina sits in a narrow valley surrounded by rocky mountains and is transformed each year into a vast encampment for pilgrims.

Muslim pilgrims touch the golden door of the Kaaba, Islam's holiest shrine.

A total of “350,000 air-conditioned tents have been pitched,” said a Saudi official.

Worshippers will climb Mount Arafat, also known as the “Mount of Mercy,” for hours of prayers and Quran recitals.

The new high-speed railway line links Makkah and Medina. Khaled Al Haj/ AFP

After descending, they will gather pebbles and perform the symbolic “stoning of the devil.”

That marks the beginning of Eid Al Adha, the festival of sacrifice, marked on Sunday.

Pilgrims then return to the Grand Mosque to perform a final “tawaf” or walk around the Kaaba.