Didn't accept it for me either; I reported it (01-May-2019). I have actually tried several variations on the "caminar" phrases as I would like to learn the possible uses of caminar. Statements like "I want to walk with my dog" (set one foot in front of the other while my dog does the same next to me?) don't make a whole lot of sense, however, any variant I tried ("walk around", "walk the city/my dog", "go for a walk", "go with") was rejected by Duolingo.
Anyone out there who knows how to use "caminar"??
Guys pay attention, when caminar is used with en, it means to walk somewhere answering where (in), not where (to).
Btw, if I want to say to walk about the city will it be caminar sobre la ciudad? And what is the difference in English between in the city and about the city?
For your second question (English usage) To walk in the city - to walk, generally, while you're in the city. Is be walking for exercise, walking to work etc, it's not specified. To walk about the city, or to walk around in the city, it's more specific, implying you want to see/experience more of the city or are going to have a longer, more wide-ranging walk.
To or In is correct. There are so many inconsistencies in this app.