Well, firstly: "Is this sentence correct?" Yes, it is correct. You can use "very" if you like. It just serves to emphasize the special nature of the event.

Something is either the best or it is not the best. 'Very' is one of the most overused words in English writing, and if you don't have a good reason to use it, don't. Likewise, something is either unique or it's not; rare or it's not.