More than 90 heads of state are on their way to South Africa for what is expected to be the largest gathering of world leaders in Africa's history.
It's a clear sign of what kind of impact Nelson Mandela left on the world.
Mandela, the activist who spent 27 years in prison before becoming his country's first black president, died Thursday at the age of 95.
U.S. President Barack Obama left Washington for Johannesburg on Monday morning to attend the memorial service for Mandela, which will take place Tuesday in the city's soccer stadium. The 90,000 seats probably won't be enough to house the many mourners wanting to pay tribute to the great anti-apartheid leader.
A state funeral will be held Sunday in Mandela's ancestral hometown of Qunu in the Eastern Cape province.
At least 91 heads of state and 10 former heads of state have said they're going to South Africa this week, government international relations spokesman Clayson Monyela said.