message: Increase National Monument cost
diff: <Description>TXT_KEY_BUILDING_NATIONAL_MONUMENT</Description>
  <Civilopedia>TXT_KEY_BUILDING_NATIONAL_MONUMENT_PEDIA</Civilopedia>
  <Strategy>TXT_KEY_BUILDING_NATIONAL_MONUMENT_STRATEGY</Strategy>
  - <Advisor>ADVISOR_MILITARY</Advisor>
  + <Advisor>ADVISOR_ECONOMY</Advisor>
  <ArtDefineTag>ART_DEF_BUILDING_NATIONAL_MONUMENT</ArtDefineTag>
  <PrereqTech>TECH_HERITAGE</PrereqTech>
  <GreatPeopleUnitClass>UNITCLASS_GREAT_ARTIST</GreatPeopleUnitClass>
  <iGreatPeopleRateChange>1</iGreatPeopleRateChange>
  - <iCost>250</iCost>
  + <iCost>500</iCost>
  <iHurryCostModifier>50</iHurryCostModifier>
  <iAdvancedStartCost>-1</iAdvancedStartCost>
  <iMinAreaSize>-1</iMinAreaSize>
  