The center of celebrations is Mihintale, the ancient monastic complex where the royal missionary monk along with his enlightened sister gave a sermon to the island's ruler. Anuradhapura, the ancient capital, is also a place where large crowds of pilgrims converge. Mass religious observances and illuminated pageants are part of the celebrations.
For the island's Buddhists, this sacred day is second only to Vesak. Long lines of devotees dressed in white climb the many steps to the top of Mihintale stone outcropping -- a kind of Plymouth Rock (Mihinthalaya) -- first to the temple then to the pagodas (dagabas) adorned in the nearby hills. The top of the rock is where Arhat Mahinda delivered his initial discourses.
Many religious activities are organized during Poson such as virtue (sila) campaigns, Bodhi tree rituals, dana-salas (freely donated food and refreshments), devotional songs, parades, and lanterns.
Many temple fill with Eight Precept devotees and pilgrims from all over the island to mark the event. The devout are clad in pure white -- just as in the Buddha's day -- with no adornments like make up on their way to temple. There they spend the next 24 hours actually practicing the Dharma in quiet contemplation or meditation.