At over 10,000 feet, Leadville is the highest incorporated city in North America, which means the sky's the limit for this weekend's Boom Days the 57th annual celebration of Leadville's mining heritage. The food and crafts fair that opened yesterday will continue today, with such Boom Days mainstays as jackleg-drilling, hand-mucking and spike-driving competitions joining the lineup; the parade kicks off at 10 a.m. And tomorrow, there's burro racing in a number of divisions, as well as a pie-eating contest. But you're bound to get a bang out of Boom Days' special presentations this afternoon at the Tabor Opera House, the Victorian marvel that Horace Tabor bestowed on Leadville back in the days when he was romancing that minx Baby Doe. At 2 p.m., Buffalo Bill or a reasonable facsimile hits the renovated stage with tales of the Old West; at 7 p.m., Duke Davis and his band, Buckshot, will present Westward Ho!, a ninety-minute musical performance with 27 songs stretching from the end of the Civil War to today. For ticket information on both shows, go to www.taboroperahouse.net.