In the Netherlands, the Dutch government announced on May 6th, 2020, that museums may reopen per June 1st, under a strict protocol of social distancing and a controlled number of visitors.
Haus der Kunst in Munich will reopen to visitors on May 11th, 2020.
In Valencia we are still in Phase 0, whether we would be allowed to enter into Phase 1 is as uncertain as the measures that are being taken to makes us go forward. However, one thing is for sure: the power of Art will overcome this whole situation!
In Spain there are different phases from 0 to 4. In Madrid we are in 0 phase but other cities are in phase 1, so will need much more time to “re open” in my point of view.
Due to the German federal state you are living in the museums are allowed to open for public again. In Lower Saxony Sprengel Museum Hannover opened on 7th of May again under certain conditions. Visitors as well as employees have to wear masks. In addition to that there is just a restricted number of visitors possible to be in the museum. There are no guided tours but there are short explanations in the lecture hall (auditorium) for just 35 people so that the distance rule will be complied. If anyone is interested in further details, please do not hesitate to ask. I will try to answer all of your questions.