Do you know when the longmen caves are illuminated in the evening? Can it be also seen from outside?

Yes, they are illuminated in the evening, also very fascinating! That is why its operating is till 22:00 during the peak season (usually from Apr. to Oct.) You can even see that in a long disdtance, but it is worth a close visit.

And yes, taxis are available back to the town at night! Don't worry.