There was in a Jerusalem city wall, a narrow gate known as the "eye of the needle". It was very difficult for a camel to pass through this gate. Either the camel would have to be unloaded or pass through on its knees.
There is a slight problem with this explanation, in that there is no evidence there ever was such a gate.
In the fifteenth century, some theologians presented the notion that the "eye of the needle" was to mean a small gate entrance to a city. Apparently the architect designing the gates, forgot about all the camels that needed to get inside the city!
Luke clears this up, by carefully using the Greek word for a surgeon's needle, nullifying this interpretation. YAHshua selected the eye of the needle because it was the smallest opening. The rope because it was an impossible situation.