Fortín Boquerón is one of the most important Chaco War sites, remembered for the fierce 1932 siege in which Paraguay retook the fort from Bolivian forces. The site now has a museum complex with photographs, weapons, memorials, and surviving defensive trenches.
The old trench line and small military cemeteries make the battlefield easier to understand than a museum room alone. Go with a guide if you can, and treat it as a serious excursion from Filadelfia or Neuland: the heat, distance, and Chaco roads matter.