Vintage fashion festivals are common in Europe. As an example, this Italian holiday, which captures the whole "village" (this is by local standards, in fact it is a fairly decent-sized medieval town) - Senigalia - in late July - early August.
The main theme is actually dance - all types of swing dancing from lindy, jazz, balboa to boogie and rockabilly. But all the same, it all comes down to vintage fashion - dancers try to dress up like they saw in pictures and photos of past years. Summer Jamboree seems to be assembling exclusively stands with vintage clothing (and some modern retro-style brands), where you can roam and buy yourself a dress, blouse, hat, swimsuit, and your cavalier - pants, shirt, shoes and so on. The main thing is that they will tell you what of what era, if you still do not understand what to combine and how to wear. In addition, of course, you can see how others dress, here the eye just rejoices: with taste of dressed people there are more than enough, half of Europe comes together, it seems.