Way back in 70 AD, for example, the Romans started building the Colosseum. Still standing today, it measures 510 feet wide. Over in France, meanwhile, the Eiffel Tower opened in 1889, at a height of about 984 feet (not counting antennas). No wonder, then, that humanity’s attention soon turned toward making other big, bold things: Big planes, big trains, and yes, big boats. In fact, in terms of boats, they, like buildings, just kept getting bigger. “Boats” became “yachts,” then “megayachts.” Now we hear “megayacht,” “superyacht,” and even “gigayacht” to refer to the biggest yachts in the world.