Suddenly the musicians in black suits begin to play Brahms' lively Hungarian Dance No. 5 in front of the Römer.
About 20 musicians from the Frankfurt Radio Symphony will gather there on Wednesday evening with their new chief conductor Alain Altinoglu for a flash mob.
The sky is blue, the Römerberg well attended, a crowd quickly gathers.
The orchestra plays well-known classical pieces: Johann Strauss' Danube Waltz and two pieces from Grieg's Peer Gynt Suite.
The musicians are obviously having fun, the audience clapping along with Offenbach's Can-Can.
“It's important that the orchestra is part of the city,” says Altinoglu.
He is happy to also reach people who are not used to classical music.
There is a spontaneous break for a carillon in the Old Nikolaikirche.
“It's great to see the new conductor so closely,” says a mother with two children who happened to drop by.
For them the flash mob is a “nice present”.
An hour later the orchestra moves on to the Zeil - and plays the same program in front of the MyZeil department store.