We will be in Budepest in Sept when the festival will be going on. My question is whether we need to buy tickets way in advance for some of the events at the temple?? Also, we will have 3 days...understanding that we do not want to try to see everything and rather go at a reasonable pace..what would be the must see sites?? Thanks
It's a fun event. Most of the concerts are sell outs, so yes, get your tickets early.
Here is last year. Keep an eye open for the 2019 update
As for what to see. That is up to your interests. My favorite guidebook is (sorry Rick) https://www.amazon.com/Top-Budapest-Eyewitness-Travel-Guide/dp/0241364698/ref=sr_1_4?keywords=DK+Eyewitness+Travel+Guide+Budapest&qid=1555605639&s=books&sr=1-4
Once you figure out what you are interested in, then maybe i can help.