The 475-foot "drop tower" in Bremen, Germany, is not a rocket disguised as a building, but a giant hollow tube used for experimentally dropping things—letting go of objects, watching them plummet toward the ground, and using those nearly 10 seconds of free-fall as a way to study the effects of weightlessness.
Fear not that scientists simply drop lead weights or billiard balls. No—they are much more interesting than that. They also drop fish.
The structure—only 360 feet of which is actually used for dropping—has been put to work with the fantastic goal of "inducing motion sickness in fish," as zoologists R.H. Anken and R. Hilbig explained in a 2004 paper published in Advances in Space Research.
Indeed, Anken and Hilbig point out, previous experiments performed elsewhere had already shown that fish "reveal motion sickness" when they "transition from 1g to microgravity." They thus did the next most obvious thing—what any of us would have done—they rigged a "camcorder-equipped centrifuge" and they started dropping fish.
Image courtesy of H.F. Wiebe Group.
Because it can be both difficult and expensive to test the effects of microgravity on human subjects, "other vertebrates such as fish are therefore used as model systems," Anken and Hilbig explain.
This means, specifically, that a little fish falling inside a tower in Germany is being studied—or, rather, "the microgravity-induced behavior of [that] fish" was under investigation—for what its descent might reveal about human astronauts in space.