In verses 5-31, Jesus predicts the destruction of Jerusalem and the temple, which will happen before his generation passes away (v. 30). He saw the near-future and accurately predicted it. In verses 32-37 he talks about the day or hour of his Second Coming, which has not yet happened for the past two thousand years (and counting).
These chapters are on Jesus’s discourse about the destruction of Jerusalem and the temple (AD 70) and then the Second Coming, which has not happened yet, 2000 years later (and counting). Looking at the chapters side by side clarifies what he really taught.
Things are not so clear-cut as I had thought they were. Please be sure to check out my photos of the Arch of Titus at the end; they show rhe Romans stomped all over the Jerusalem temple.