Nepal resonates with the sound of OM MANI PADME HUM. Many Buddhists (or at least Tibetan Buddhists) believe chanting this mantra brings special blessings. However, if one gets tired of repeating the phase vocally, spinning a wheel on which the words are written can provide the same benefits. The most ingenious prayer wheel I saw was deep in the mountains. The enterprisingly pious individual at one household had built a rather large prayer wheel beside a stream and provided a mechanism by which the passing water turned the wheel and sent the prayer toward divinity all day long.
Around the cities in the Kathmandu Valley, prayer wheels are often found near sacred sites, where visitors can spin the wheels as they pass or pilgrimage and hope for divine favor.