The answer is: St. Petersburg
As I recall it was rolled-steel girders riveted together, probably from shipbuilding, together with steam-powered winches and an abundance of cheap steel. As opposed to European cathedrals erected with animal-powered winches and with more expensive forged iron bracing (one of the big cathedrals has a kind or iron corset to keep the walls from bursting outwards).
The correct answer is Rhapta. The area of Rhapta was historically famous for being a trading port for people of all nations and it was located in Southeast Africa. It was first described in the 1st century AD. There's even evidence that Romans traded there as well.
A does not make any sense to me i hope this helps