Summer’s last stretch collides with autumn’s first arrivals this week. Letní Letná and Prague Harley Days both close out for good (or at least for this year), a Polish street artist is finishing a monumental lace mural in Žižkov, and by the weekend, the city’s classical calendar shifts into high gear with the Dvořák Prague Festival’s starry opening night. Here’s what’s worth putting on your calendar this week: