When the holidays come to western Nevada County, residents have two prominent options for festive street affairs each week: Grass Valley’s Cornish Christmas and Nevada City’s Victorian Christmas. The two events have no shortage of similarities and their final occurrences of the year are Friday and Sunday in Grass Valley and Nevada City, respectively. Both shut down the main thoroughfares in each town’s historic downtown district, leaving the streets to be filled with merchant booths selling everything from kettle corn to art and crafts. Businesses keep their doors open later than normal for these events and residents and visitors alike …