The narrowest street in Prague is located in the Malá Strana neighborhood. Just take U Lužického semináře street and you will find it at no. 24.
Measuring about half a meter wide, it is equipped with traffic lights on both sides lest passers-through collide.
The street leads to a restaurant and is only open when the restaurant is (daily 11.30-00.00).
To take a look at another very narrow street, check out the narrowest street in Venice.