User blog comment:Brittleigh2211/Special Event/@comment-12932576-20140220162307

Brit,

You are correct, once the event is over, you will not be able to build the final building if you had not started it before the event ends. Next years event will likely be a different final building as well, and use different resources(not rings) to get it. So if you can afford the gold coins for rings right now, go for it.

On the Christmas event, you actually may very well be able to just upgrade it next year when the even comes through again, players were able to do just that this past year(having started it the year prior and finished upgrading this turn.

Even if you couldn't upgrade any further, it is still a high money earning building even at lvl 3 and 4, well worth keeping IMHO.