Exegesis:

eis tas kōmas Kaisareias tēs Philippou ‘to the villages of Caesarea Philippi’: i.e. villages surrounding Caesarea, the most important city of the region.

en tē hodō (cf. 8.3) ‘on the way,’ ‘as they went.’

tina me legousin hoi anthrōpoi einai literally ‘whom do men say me to be,’ an indirect form with the infinite of the verb, rather than the direct form, with the present indicative, tis legousin hoi anthrōpoi hoti egō eimi ‘Who do men say that I am’: it is this indirect form, with the infinitive, which determines the accusative case of ‘John the Baptist’ and ‘Elijah’ in the next verse.

Translation:

Caesarea Philippi should be treated as a unit proper name, referring to a region, e.g. ‘the region called Caesarea Philippi,’ rather than attempting to translate as ‘the Caesarea of Philip.’

On the way may be best treated in some languages as a description of a process, e.g. ‘as they were walking along’ or ‘while they were journeying.’

Who do men say that I am is essentially a complex expression, for the predicate complement of the verb am is the object of the verb say. In some languages such a construction is impossible, but an equivalent may be found in ‘Men talk about me. What do they say?,’ ‘When men speak about me, what do they say?,’ or ‘When men talk about me, what person do they say I am?’ (this last expression comes closest to the force of the Greek). Cf. Indonesian ‘Who am I according to the saying of the people?’

Quoted with permission from Bratcher, Robert G. and Nida, Eugene A. A Handbook on the Gospel of Mark. (UBS Handbook Series). New York: UBS, 1961. For this and other handbooks for translators see here .