The Prague Information Service (PIS) provides information about concerts, performances, and other city events. PIS also sells public transport tickets. They have maps and publish a monthly guide for tourists. Their English-speaking staff is very knowledgeable and helpful.
Prague information service offices:
Old Town Square 1, Old Town Hall; Open: 9am-7pm Apr-Oct, 9am-6pm Nov-Mar
Rytirska 31, Old Town; Open: 9am-7pm Apr-Oct, 9am-6pm Nov-Mar
Main Railway Station (in the lobby); Wilsonova 2, New Town; Open: 9am-7pm Mon-Fri, 9am-4pm Sat & Sun Apr-Oct, 9am-6pm Mon-Fri, 9am-4pm Sat & Sun Nov-Mar)