In 1621, 27 Protestant lords were beheaded on Prague's Old Town Square, and a dozen of their heads were mounted on the Charles Bridge tower as a reminder not to cross the Habsburgs. That sort of thing tends to stay with a place.

The square has been Prague's beating heart since the tenth century, when a marketplace sprang up at the crossroads of Europe's trade routes. Its astronomical clock, installed in 1410, is the oldest still running anywhere. The Týn Church holds Tycho Brahe, the Danish astronomer who wore a silver nose after losing his real one in a duel. Kafka, who grew up on the square, said of it, "Within this little circle, my whole life is enclosed."

VoiceMap's self-guided audio tours trace Kafka's footsteps through the square, explain how Jan Hus inspired Martin Luther a century before the Reformation, and uncover the salon where Einstein played violin.