CvPlot

One object for each tile of the map. GC.getMap().plot(x, y) returns the tile at those coordinates, or null when they are off the map.

What is on it: CvPlot::getTerrainType, CvPlot::getFeatureType, CvPlot::getResourceType, CvPlot::getImprovementType and CvPlot::getRouteType (roads and railroads). Given a team, CvPlot::getResourceType hides a resource that team cannot see yet; leave the team out to get the real one. CvPlot::getPlotCity gives the city on it, if there is one, and CvPlot::getNumUnits and CvPlot::getUnitByIndex its units.
Who has it: CvPlot::getOwner gives the owning player's ID, and CvPlot::setOwner changes it. CvPlot::getWorkingCity gives the city whose citizens may work it.
Yields: CvPlot::getYield reads the yields the game stored, and CvPlot::calculateYield works them out again.
What each team sees: CvPlot::isRevealed is true once a team has seen the tile, and CvPlot::isVisible while the team can see it now.
Turns: CvPlot::doTurn runs once a game turn for every tile, not once for each player.

Functions