In John 5:2, we read:
Now there is (Ἔστιν) at Jerusalem by the sheep market a pool, which is called in the Hebrew tongue Bethseda, having five porches.
Some have pointed to the use of the present of ειμι as evidence that John was written when this pool was still around, and, therefore, wrote before the destruction of the temple in AD 70. I am rather sympathetic towards dating the gospels pre-70, and I do believe there are good evidence for such, even if such is a minority perspective. Commenting on the use of the present tense, Daniel Wallace, a leading grammarian of the Greek New Testament, wrote:
2) John 5:2
The text reads: ἔστιν δὲ ἐν τοῖς `Ιεροσολύμοις . . . κολυμβήθρα (“Now there is in Jerusalem . . . a pool”). Since εἰμί is nowhere else clearly used as a historical present, the present tense should be taken as indicating present time from the viewpoint of the speaker.49 The implication of this seems to be that this Gospel was written before the destruction of Jerusalem in 70 CE.50 Although many object to a pre-70 date for John’s Gospel, they must, in support of their view, reckon with this text.
Notes for the Above
50 By arguing that ἐστίν is a stative present, we are admittedly going against the tide of NT scholarship. Generally, NT scholars have attempted to circumvent the prima facie force of ἐστίν by adopting one of five approaches in this text: (1) ἐστίν is a historical present (so Schnackenburg, Knabenbauer, Carson, et al.); (2) ἐστίν is an anomalous present (McNeile); (3) the author erred, not knowing that the pool had been destroyed (Bleek?); (4) the pool of Bethesda must have survived the Jewish War (Plummer, Dods, Tholuck, Weiss, et alii suggest this, but prefer the historical present view [but Jeremias assumes it]); (5) the redactional view: John 5:2 belonged to an earlier stratum of the Gospel, only to go uncorrected in the final publication (MacGregor, Brown?). Each of these views has severe problems. See Wallace, “John 5,2,” 177-205.
Source: Daniel Wallace, Greek Grammar Beyond the Basics: An Exegetical Syntax of the New Testament (Grand Rapids, Mich.: Eerdmans, 1996), 531
For more on this interesting from Daniel Wallace, see: