Sandomierz is a historic town in south-eastern Poland with 23,863 inhabitants, situated on the Vistula River near its confluence with the San, in the Sandomierz Basin. It has been part of Świętokrzyskie Voivodeship since its transfer from the Tarnobrzeg Voivodeship in 1999. It is the capital of Sandomierz County. Sandomierz is known for its preserved Old Town, a major cultural and tourist attraction which the President of Poland declared a National Monument of Poland in 2017.

Tarnobrzeg is a city in south-eastern Poland, on the east bank of the river Vistula, with 49,419 inhabitants, as of 31 December 2009. Situated in the Subcarpathian Voivodeship since 1999, it had previously been the capital of Tarnobrzeg Voivodeship (1975–1998). Tarnobrzeg lies in the Sandomierz Basin, and directly borders the town of Sandomierz, Świętokrzyskie Voivodeship. Its history dates back to the year 1593, when it was granted Magdeburg rights, and belonged to the Tarnowski family. For centuries Tarnobrzeg remained a small town, which did not develop until the post-World War II period, when it became center of an industrial area, based on rich sulfur deposits.