Are they expecting a narrative, or doco, or are they just wanting anything?
If you want to make some arty nonsense that film schools usually like, then maybe go with 'Love in Berlin' and hunt for images that show love.
for instance, accidental heart shapes in nature, the angels on the cupola of the Berliner Dom, Gloria on the Siegessalle (sp?), the christ in the Church by the zoo (forgot the name - friedrich wilhelm or something), monkeys cuddling in the zoo. You get the picture (so to speak)
The city is probably full of love images. you could also use some of its not so lovely history as a counterpoint.
Just a thought.