Mark 13, evidence for when MArk was written or how Mark was written?

Mark 13:2 "Not one stone will be left here upon another; all will be thrown down.”
This NEVER occurred. Some stones were indeed left one on top of another. Therefore, Mark is written begore the actual fall of Jerusalem and destruction of its temple, but at a time when it was foreseeable... so 68 or 69 CE fits this evidence.

Mark 13:14 “But when you see the desolating sacrilege set up where it ought not to be (let the reader understand), then those in Judea must flee to the mountains;
This would seem to describe the construction of Aelia Capitolina either in 130 or 135 CE either just before or just after the Bar Kochba revolt.

A simpler explanation may be in order. Mark is describing a destruction of Jerusalem and its temple. But he does so by using prior texts. Jesus's 'not one stone left on another' is an inversion of Haggai 2:15 "But now, consider what will come to pass from this day on. Before a stone was placed upon a stone in the Lord’s temple," Haggai is describing the construction of the temple. Mark is describing the destruction by inverting the construction in Haggai.

Likewise, Mark uses the phrasing from Daniel, which was written to describe the cleansing and rededication of the temple near 168 BCE. Daniel represents a 'time of the end.' In the case of Daniel it is the end of the Seluekid rule that is described. In the case of Mark a new dynasty marked the end of the Julio-Claudio dynasty that ended poorly with Nero.

13:30 Truly I tell you, this generation will not pass away until all these things have taken place. "

9:1 And he said to them, “Truly I tell you, there are some standing here who will not taste death until they see that the kingdom of God has come with[a] power.”

These are predictions from the perspective of the main character Jesus, but not to Mark, writing sometime after these events have taken place. 'The end' did take place. A new government has been establisehd, both by Vespasain's victory in Rome and titus's victory in Jerusalem. It can be argued that this is a very pro-Roman sentiment. It can also be argued that it follows naturally from Jeremiah, where Nebuchadnezzar was sent to punish Judea by YHWH. In Mark and Jeremiah, YHWH's righteous judgement found Jerusalem wanting.

So I cannot say WHEN Mark writes, other than it is post 70 CE. But I think I can say HOW Mark writes. His use of prior texts to tell his story overrules the details of a historical narrative.