Seems like Avant Garde Gothic Bold. The words "This Infinite World" seem to be stretched, or there is another vendor with an expanded version.
Don

Thought also to Avant-Garde but I don't think that's it. Too many details look off to me (digits, /e...) and the Bold weight is far not enough bold. I thought also to Graphik and Fakt but even after playing with alternates, that's not it either. Still searching.

Before posting the suggestion of Avant Garde Gothic Bold I ran the letters & numbers through Identifont, which suggested only Fakt. I checked the same link you posted and rejected Fakt mainly on the width issue, as its widest version was even narrower than Avant Garde Gothic Bold. I found nothing else that matched, even on some sites such as Hoefler & Frere Jones that don't show up at MyFonts.
Since this was a sign for an artistic event, I went with the possibility of Avant Garde Gothic Bold expanded by the sign designer.
So I wonder what else is out there. A "free" font? An in-house font by the museum? Something by a German foundry that I missed?
The image posted by July has excellent detail but is hard to read without a kink in the neck. Here it is, rotated 90 degrees, and rearranged so it's easier to check letters. Ignore the jagged letter edges that appear in parts of the image. They are artefacts from a quick & dirty geometric distortion correction.

Very interesting, I agree. Thanks a lot, Don! Also for rotating the image ;-)

You're welcome.
Don