The answer is Stuttgart, or the Johanneskirche at the Feuersee, to be precise.
Acoording to won information, this is a unique pop-up-location where cuisine, culture and keynotes can be combined with each other. This coming winter, the pop-up-event HeavenSevenEleven returns to the Johanneskirche at the Feuersee. Interested parties can book for the period 21.01.2019 to 23.02.2019. There is space for events with 20 persons up to about 300 persons.
More information is available here on the German website.