The rules say that once the monument is built in the 3rd round, the game ends, and you don't loose points for extra bricks you have left over.
BUT, what if you are unable to place bricks in the 3rd round, and have to pass. Do you loose points then?
This is an ambiguous situation , as the rules as written do not explicitly state whether a player loses points for extra bricks after the third round (assuming that the monument has not been completed).
If you look at the following paragraph on page 4 of the rule book:
The game ends after the third game round. If the monument is finished earlier, the game ends immediately, and players do not lose points for construction tokens that remain behind their screens. The emphasis implies that if the monument is not completed then the player would lose points for extra construction tokens. At least, this is how our group has chosen to interpret the rules. YMMV.
I think that you could argue either point effectively. Just have everyone agree about end of round scoring before playing.