The carriage carrying Lucifer suddenly stopped while Lucifer was still feeling the city to make sure that there would be nothing that would be able to mess up with his plans.
And it was because of this that Lucifer knew where they stopped.
'Hmm? We stopped in one of the 6 main buildings, and what's more, this is the building where the gathering is happening...'
Right, they stopped at the main building where the gathering is happening.
Lucifer was able to feel this gathering ever since they entered the Warm City since there were just so many people here.
That was also why he was able to notice them right away when he felt that the carriage stopped running.
Incidentally, Lucifer could also feel that the other carriages that went with their carriage have gone in other directions now.
Some of them stayed with Rouge's carriage, but...most of them went towards other directions.