Petržilkovský Island is the smallest island on the Vltava River. It is 60 meters in length and only 10 meters in width. It lies above the Children's Island in the Smíchov district. It is not publicly accessible.
During the Hussite wars the Old Towners seized part of the Kampa Island and the Lesser Town river banks, and therefore the Lesser Towners had no choice but to build their water tower outside the city perimeter. They took advantage of the fact that in 1483 the New Towners enabled the Lesser Town townsman, the baker John Petržilka, to build a new mill. In the years 1547-1561 the Island was confiscated by King Ferdinand I of Habsburg. In 1859, the island was bought by the city of Prague.
During the construction of the lock in Smíchov in 1911-1922 part of Petržilkovský island became part of the Jewish Island (today the Children’s) and the rest was considerably reduced. The island is so small there even some maps do not include its name.