There is a special class of noun phrases in English that have the ability to function as adverbial modifiers, unaccompanied by a preposition or any other indicator of adjunct status. These are the so-called bare-NP adverbs. Here are some examples:
(1) I saw John [that day]. (2) I saw John [someplace you'd never guess]. (3) John was headed [that way]. (4) Max pronounced my name [every way imaginable].
As I was wondering if there is similar phenomenon in German, a sentence came to my mind:
(5) Eines Tages geht er auf der Straße spazieren.
Can "Eines Tages" here be regarded as a bare-NP adverb? Are there other similar examples in German?