Nepal's king and prime minister have joined hundreds of mountaineers to celebrate the 50th anniversary of the first ascent of Mount Everest.  Thursday's ceremonies culminate a week of festivities honoring the mountain and those who climb it. 

Sir Edmund Hillary is the guest of honor for the day's events.  Mr. Hillary and his Sherpa partner, Tenzing Norgay, were the first humans to reach the top of the world, on May 29, 1953. 

Nepal's King Gyanendra and Prime Minister Lokendra Bahardur Chand are hosting a gala dinner for Mr. Hillary and hundreds of other climbers who have reached Mount Everest's summit. " I have many memories of those great days on Everest," said Sir Edmund Hillary. " Memories of difficulties and danger and of comradeship and of team spirit.  We were the lucky ones 50 years ago.  We had to cross difficult crevasses ourselves, cut steps on icy slopes and never walk in other people's footsteps.  There were not any steps there except our own." 

During observances and festivities leading up the anniversary of Mount Everest's ascent, Mr. Hillary has reminded his audiences that push to reach the summit was a team effort.  Neither man, he says, would have reached the summit without the help of the other. 

Tenzing Norgay died in 1986.  His son, Jamling Norgay who himself reached Everest's summit in 1996, says his father would have liked nothing better than to have been by Edmund Hillary's side in Kathmandu to mark the 50th anniversary of their joint triumph.  Jamling Norgay says his father was an exceptional climber who was not much changed by his triumph on Everest. " People in those days used to say he had three lungs," he said. " That is how efficient he was.  He worked really well in high altitudes.  But he was a very simple man, a very humble man, before he climbed the mountain.  Even after he came back down the mountain a hero, he remained the same person until he died." 

More than 1,300 climbers have reached the summit of Everest and about 175 have died trying. 

In the days leading up to the anniversary of the first ascent, a series of records were broken, including the fastest ascent and records held for the oldest and youngest climbers to reach the summit. 

In recent days, Edmund Hillary has criticized environmental damage on Everest and has called for a moratorium on expeditions, to his words, "give the mountain a rest." 

He also says commercial climbing expeditions that take inexperienced climbers to the top of Everest have diminished the experience of climbing the world's highest mountain.