Pertinax posting reminded me of my excitement at my first visit to Basel - a couple of years after his, as the gorillas were in what was then the new Ape House.
I have scans of my two favourite photos from that day and I have just posted them in the Gallery - not wonderful quality, but no gorillaholic will fail to understand their significance

I can't think of a better way to welcome you (unless someone can add photos of Baron Macombo & Millie~Christina)
Gentle Lemur- my first visit to Basel in 1969 the Gorillas had recently been moved into the new Ape House and the group had been altogether for just a short while I think. Stephi had lost the hair on his upper arms, stress either from the move to new quarters or the close proximity of the unrelated younger silverback Pepe whom by subtle postures he forced to stay on his own in the far right hand cage. Did you see the old cages in the Bird House(its gone now) where they used to live and breed- they were very small indeed.
I really like your photo of Stephi(or Steffi)- I believe I've seen it before so has it been published? He was a superb male and very photogenic. He passed on his distinctive looks to his two younger offspring- Migger(who was another superb male) & Quarta, while Goma & Jambo look(ed) like their mother Achilla. Quarta's daughter Faddama in the current Basel group also has the distinctive looks of Stephi too..
You mention Baron & Christina- I have photos of them though I never saw them (another story...). You'll know that Stephi was originally the youngest member of the trio at Columbus. I am pretty sure that Christopher/Stephi and Christina were closely related(half siblings?) as they were captured from the same wild troop by Bill Said while the considerably older Baron came from a different area(have you read the book 'Gorillas in our Midst- the story of the Columbus gorillas? by Jeff Lytle- an interesting read but with some inaccuracies) Anyway, you'll know Christopher/Stephi was later traded to Basel Zoo while Baron & Christina bred 'Colo' at Columbus. The interesting thing is that as an adult, 'Colo' has exactly the same facial appearance as her 'uncle(?)' Stephi at Basel- quite uncanny...
Now I see that Basel are finally building large outdoor enclosures for all their Apes.
I will try and copy the Baron/Christina photos that I have...