Inside the walls of Prague Castle there are buildings dating as far back as the 9th century. Even the newer ones are from the Romanesque, Gothic and Renaissance periods, and together, along with the formal gardens, they make up one of the largest castle complexes in the world.
Along the north side there is a wild glen called Jelení příkop (the Deer Moat), originally part of the Castle’s fortification and later a private hunting ground for the king. The royal stock of stags (and even a few bears) is gone, and today the Deer Moat is a public park of inviting lawns and shaded woods, with a stream channeled down the middle. It’s all easily traversed via stone steps, paved paths, swinging timber walkways, and a 275-foot (84 m) pedestrian tunnel that runs underneath the famous Powder Bridge.
The opening up of the Deer Moat and building of the tunnel were pet projects of former President Václav Havel, who wanted to give visitors an easier way to take advantage of the extended Castle grounds. He brought in Czech architect Josef Pleskot to design the tunnel, which incorporates the moat’s stream, much of which had been relegated to underground pipes in the late 19th century.
Pleskot kept the stream, called the Brusnice, as part of the overall underground experience of the tunnel, an oval tube of elegant brick work that feels at once enveloping and expansive. The sloping curve of the walls was designed to create this sense of comforting roominess, to belie the tightness of the quarters–no doubt making some grateful claustrophobics in the process.
Update as of October 2019: The Deer Moat is closed for the rest of the 2019 viewing season due to reconstruction. No opening date has been confirmed.