Also known as aquastats or hydrostations, the submersible cities of the Eurasian Alliance
The Rock of Gibraltar, once a stalwart of British power, the gate to the Mediterranean, now is a fortress for the Eurasian Alliance. It's fair teeming with neo-Soviets and submarines.
Surnames: The Chinese were among the very first cultures to adopt the use of hereditary surnames (around 2800 BC). But the custom didn't quite catch on in Europe - at least not until the Venetian aristocracy made it popular sometime between the 10th and 11th centuries AD. What culture made it popular in your setting and why?