There is a rule in Judaism that most doors must have a "mezuzah" on them. This is a Biblical-level commandment.
Last night, I noticed that the hotel I am staying in had a mezuzah on the revolving door:
I had never seen a mezuzah on such a door before, and it struck me that the halachic questions of how exactly to place such a mezuzah almost all come from Israel. Does it tilt towards the door or the inside of the building? Is it placed on the round part or the flat part next to the door?Halacha, Jewish law, must innovate to handle new circumstances, and Israel is the place that such innovation is coming from. While a mezuzah may seem a trivial example, it points to the fact that Israel is where the new questions are more pertinent and therefore the place that even the most religious interpretations of Judaism is forced to adapt to the modern world, out of necessity. This makes Judaism relevant to every day life here in ways that one cannot see anywhere else in the world.