The Koran requires every Muslim who is physically and financially able to make a pilgrimage to Mecca, home of the Prophet Muhammad and birthplace of Islam in the 7th Century. The pilgrimage, known as the hajj, reaches its climax this week. More than two million people are in Mecca, including thousands from the United States. Lonny Shavelson met with some of them as they prepared for the emotional journey.

The hajj is the largest pilgrimage in the world. Muslim faithful gather in Mecca as they have every year for 14 centuries. The pilgrims perform a series of rituals. They walk in a sea of humanity around the holy kabah. The granite structure stands in the courtyard of Mecca's sacred mosque, a symbol of the centrality of God. It's the focal point for Muslims the world over when they face Mecca to pray.

It takes weeks to get ready for the hajj, whether you're in Saudi Arabia, North Africa, Pakistan ? or California's Silicon Valley.

Omar Bellal is a software engineer, but on this late November day he's at a mosque in Fremont, leading a hajj class of 35 Muslims who will join 12,000 others heading from the U.S. to Mecca. He is showing them PowerPoint slides. "Using this wonderful tool, the Internet, [there is] a lot of information there," he explains, "that is a gift from God, and as soon as you get it you have the duty to share it with others."

Bellal's high-tech presentation instructs the students in the rituals of the hajj. "Get as close as possible to the kabah," he tells them, "because your circuits will be shorter. Even though it will be a little more crowded, you go around the kabah in this direction seven times. Ten minutes for each circuit."

The students are mostly well-educated men from the tech industry, with origins in Afghanistan, India, Pakistan. They take copious notes: bring an MP3 to listen to Islamic lectures while traveling; take socks, the marble floor is hard on bare feet; don't forget your string of beads to keep track of how many times you circle the kabah. Bellal encourages his class to try, if they can, to get through the dense crowd to the ancient cornerstone of the kabah. "If you get to the blackstone, then you can kiss it and put your forehead on the blackstone."

What's not discussed in hajj class is that the students are about to travel in packed crowds of Muslims from every Islamic country, who in these times may not have the most favorable opinion of Americans.

A week after the class, student Shafiq Jamal arrives at a family gathering the night before his flight to Mecca. Jamal's parents are from Afghanistan. He was born and raised here and is an electrical engineer. As he prepares for the hajj, he says he feels isolated. "Nobody else in my peers understands the preparations that I need to do, that I'm leaving my newborn son with my wife here and going away for three and a half weeks. Anybody else would look at it and say, 'Look, what's wrong with you?' If you say 'Hey look, there's this big spiritual aspect to it' and they don't get it, at times you just have to leave it at that because there's no willingness to understand beyond that."

Jamal is worried that he may also be misunderstood by Muslims from other countries when he gets to Mecca. "I think a lot of Muslims see America as bad, as evil. I don't know if I can convince them that I'm an American and I'm a Muslim, and the U.S. has a lot of good aspects, and that's why we're here. It gives us the freedom to learn, the freedom to practice our religion."

But Jamal's cousin, Parisa Azizad, isn't worried. The college senior is also going on the hajj. She says it's a false image that Americans on the pilgrimage won't be understood by other Muslims. For the hajj, everyone wears identical clothes, walks identical steps, prays identical words, and differences fade away. "If you look at any image of people circling the kabah, you see people wearing white. You hardly see race, you don't see gender. And when you're praying you pray side to side shoulder to shoulder and everyone's even everyone's equal before God and everyone's a servant before God. And the hajj emphasizes that in such a beautiful way."

Jamal's grandfather starts the prayer for travelers. Jamal says that when he leaves for Mecca, he'll try to put aside all questions of how others view him, and focus on his pilgrimage.