Best cities for retirement in Germany

Hmmm. I have never heard of people without a connection to Germany coming here to retire. Learning the language and how to fit in at that age seems doubtful. And where to live if one does feel comfortable in Germany is totally a personal thing. Does one like mountains or the sea? Does one like rural living, small quiet communities or a big city full of cultural offerings?   

A big factor is climate and cost. Most retires who immigrate somewhere tend to look for some place with a warm or very mild climate and low costs. Neither of these really fit to Germany although climate change has been rather positive for Germany in this aspect. Although the winters were never bitterly cold, summers were often short and not always very warm. Most of the year, in most places, the weather was always in between. I remember summers in the 1980’s where one only wore shorts for a couple weeks in the summer and still needed a jacket or sweater at night. Now it’s noticeably hotter and for longer.

There are of course retirement homes throughout Germany but no particular towns or regions I know of where there is a large retirement community like one might find in Florida or the southern coast of Spain.

Although all parts of Germany have excellent old age homes and care facilities, very few foreigners come here to retire, for the reasons Tom mentioned above.
On the contrary, it is a (small but growing) trend for German retirees to move abroad, mainly to places with cheaper living and labour costs (plus better weather). There are German retiree communities in Spain and German-speaking old-age homes in Thailand!
Foreigners in Germany anyway tend to "go home" when they stop working.