Thebes: extending your turn past the end of the last year
According to the reference document at OrderOfGamers.com,


  Once players are in 1903, when a player’s marker crosses space 52 he must end on space 1. He may use no more weeks. Once all players have reached 
  the space, the game ends and scoring commences.


You must stop on week 1 of (what would be) the year 1904, and you may not use any weeks beyond that.