The Citadel of the Ten Fingers, already a structure located high in the clouds far above zone 1 of S Prime city. The only way to get all the way up there is by taking one of the designated pathway elevators in the single tallest building in S Prime, so it isn't exactly surprising for Jon to suspect that there is some hidden fascination for heights when the actual meeting is hosted on the tallest building on the Citadel still, a distinctively Chinese style of architecture with long and curved tiles on the roof, red paint and extravagant patterns all around the buildings.
When all of the Ten Fingers arrived in the Citadel literally within a span of minutes, Wan Yi took the initiative to adjust the meeting day and shifting it forward, giving the traveling fingers a day to rest and catch up with one another before getting right to business nice and early the next day.