KATHMANDU, JULY 29 Kathmandu witnessed a rare, sacred occasion on Guru Purnima today as devotees held a Dipankar Buddha procession and Panchadan ceremony at Mahabouddha, commemorating Samyak Mahadan - a tradition meant to be held every 12 years but not observed in 24 years. The Panchadan programme honoured 85 Shakya Sthavirs and Dipankar Buddhas, followed by a grand procession through the city.