Or HaChaim on Genesis 28:11/אור החיים על בראשית כ״ח:י״א

1 ויפגע במקום. He encountered the site. The plain meaning of the verse is that Jacob arrived at an inhabited place. This is why the Torah concludes the paragraph by telling us that the town where Jacob found himself spending the night had previously been named Luz. The site had been a town then, and Jacob spent the night there.

2The reason the Torah mentioned that the sun had set is simply that Jacob would have continued on his way in order to get closer to his eventual destination had it not been for the fact that nightfall required him to make camp. Bereshit Rabbah 68,9 explains that the definite article under the letter ב in the word במקום is an allusion to the site being Mount Moriah, the mountain destined for prayer and the eventual site of the Holy Temple. They base this on Genesis 22,4 where Abraham is reported as having recognised that site as the place where he was to offer up his son Isaac as a total offering to G'd. This is, of course, a homiletical approach. We naturally accept the words of our sages as absolutely true insights and they do not contradict our own explanation at all. Rashi has already explained that Mount Moriah had been transplanted for the occasion so that Jacob could offer up his prayer at that holy site.

3וישכב במקום ההוא. He lay down on that site. The Torah reports that Jacob dreamed and wants us to know that it is not the lying down that inspired the dream but במקום ההוא, the nature of the site.

4The wording also alludes to what we are told in Chullin 91, that the earth under Jacob folded up, i.e. that Jacob lay down on that whole strip of earth from Moriah to Luz. This is what G'd referred to in verse 13.