Home of the Stockholm Philharmonic Orchestra, this is the principal place to hear classical music in Sweden. The Nobel Prizes are also awarded here. Constructed in 1920, the building houses two concert halls. One seats 1,600 and is better suited to major orchestras; the other, seating 450, is suitable for chamber music groups. Besides local orchestras, the hall features visiting ensembles, such as the Chicago Symphony Orchestra. Some series sell out in advance to subscription ticket holders; for others, visitors can readily get tickets. Sales begin 2 weeks before a concert and continue until the performance begins. Concerts usually start at 7:30pm, with occasional lunchtime (noon) or "happy hour" (5:30pm) concerts. Most performances are broadcast on Stockholm's main classical music station, 107.5 FM. The box office is open Monday to Friday 11am to 6pm, Saturday 11am to 3pm.