http://hnm.hu/en/events
I happened on this wonderful festival last May when I arrived on a Sunday and had time to kill before getting into my hotel, and I loved it so much I think I'll try to attend again next May. It's free, on the lovely tree-shaded grounds of the National Museum (Kalvin ter metro stop), exhibits from museums all over Hungary and all kinds of craft demonstrations and quality handmade items to buy, some antiques and books, even. Several food stands, very cheap, music, and just a lot of locals hanging out and enjoying themselves--it was the best thing I ever accidentally happened upon.
I havent seen it yet. But I got a lot of years to go. I finally made it to the airshow this year after many, many years of wanting to see it……… only to find out it was cancled. But there was a race car with exhibition runs up and down Andreassy ut.
Here are a couple of listings
http://visitbudapest.travel/budapest-events/
https://www.budapestbylocals.com/events/
http://www.budapesteventsguide.com/
No matter where I go, I try and plan it around a special event if at all possible. Just adds another layer of discovery to the trip.
For your next trip back my two favorite events (so far) are the Nemzeti Vágta/National Gallop and the Jewish Cultural Festival, both in September; and neither of which I will see this year, the Vajdahunyadvár Summer Festival in I think June, and the Palinka and Sausage Festival in October Oh, and the Red Bull Air Race in July has to be on everyones list.
James, I thought of you when I asked my hotel about events for May Day, mentioned the air show and they said it happens in July. I did get to see some of the car racing on Andrassy ut, marveled at how easily the crowds were controlled and how well-behaved everyone was--somehow I think that wouldn't be the case here. Spent the majority of the day with the locals reveling in City Park. As I seem to need to return to Budapest annually and can't go in summer, Sept or Oct may be do-able, thank you for the suggestions--the Jewish Cultural festival and Palinka and Sausage both sound very interesting.
They'll shut down Andreassy ut for just about any reason. When we were recently there, they had a bunch of people riding bicycles going up the shut down street/boulevard.
And on the Spring Festival of Museums: Budapest has more museums than I've ever seen--over 200 total. I'm surprised they don't have a museums of museums.