I visited Berlin in November last year, and although I didn't do the Third Reich thing (I did museums instead), I did go on a Bowie-&-Iggy-in-Berlin tour thing and it was quite fantastic
I recomend it to everyone.
As for Jack the Ripper, they won't ever figure it out - there just isn't any evidence available to do so, and after c.125 years there is unlikely that any revolutionary evidence will turn up. As for the Ripper being a doctor, that is a strong posibility, but (taken from memory) the first physician to perform and autopsy on one of the earliest victims dismissed the notion outright. It is mostly in the aftermath years that the doctor theory has become established fact in various media
In all likelyhood, I feel, he was a clever madman murderer who got away whith it, possibly becase he was locked up for some other crime or insanity and was therefore kept from killing again, or he might have moved on aboard one of the countless ships sailing out of London, or he simply died and never left enough evidence to make him a suspect.