Each bid must be higher than the previous bid. A player may bid any number of times. The highest bidder gets the Explorer and deducts from his National Treasury. German Explorers may not be rented by players to other players. Instead of using the three Treasure Cities shown on the map, players may use the eight Treasure City counters instead to add variation to the game.
Players place the eight Treasure City counters face down anywhere on the map.
When any unit moves into a hex containing a Treasure City counter, the counter is immediately flipped over. If it is a blank it is immediately removed from the game. If it is one of the four Treasure Cities, it is then face up for the rest of the game and can be looted as per the normal game rules.