roman basilica in kastel fortress, banja luka, bosnia

banja luka banjaluka bosnia herzegovina republika srpska serbian republic kastel fortress castle roman basilica ruins remains fort archaeology archaeological dig site excavation excavate september summer capital grounds europe walls balkans architecture buildings old historic travel tourism town city cities bosnian european union east south eastern southern outside outdoors landmark historical ancient antiquities stone heritage monument grass rocks uncovered mound trench burrow trees portaloo inside 16th century