As the last space shuttle returned to Earth and that long-running program ended, many news articles addressed America's future in space. When you read an article about the shuttle, you often see a line about how the shuttle is the most complex machine humanity ever built. I don't know if this is true, or if it's simply been repeated so many times that it's accepted as true.
But it did bring to mind a theory I have about civilizations and their ships. Historians measure cultures past and present by many models. Their political and legal systems and the degree of freedom their citizens enjoy, like the Code of Hammurabi or the voting rights of land owners in ancient Athens. Or the size of their cities, or the complexity of their economies. Historians may examine their architecture and monuments, like the pyramids and the Coliseum. Or even their use of alphabets or the wheel.
I think we can learn a lot about the technological development of any given civilization from their ships. Now landlocked civilizations may not ever develop anything other than river craft, but cultures that border the sea often take the opportunity to build complex ships capable of fishing, war and trade.
The Phoenicians didn't just write a useful alphabet, they built ships that travelled the Mediterranean Sea to engage in trade with all sorts of other civilizations. Or consider the Polynesians--they built vessels that could handle the fierce Pacific storms and carry their people incredible distances. The Greek trireme was a mechanically complicated craft that relied on the coordinated effort of well-trained crews to propel and steer it.
Before the introduction of the steam locomotive, I think you could argue that the European three-masted ships of the line of the 1700s were the most complex machines on Earth. These ships used a very flexible system of sails for power; a combination of math, astronomy and instruments for navigation; careful storage of water, food, spare sails, ropes, weapons, and lumber to remain self-contained; carried powerful cannons with at least three types of ammunition; used semaphore flags to communicate with other ships; and examined the sea and land around them with the best optics available.
As we retire the space shuttle, we might want to look at the cruise ships and aircraft carriers and submarines the modern world produces. Aircraft carriers are often described as 'floating cities' because they carry crews of thousands and have their own nuclear power plants. Enormous cruise ships with sophisticated weather and navigation systems carry passengers in luxury across the world. And submarines plunge deep into the ocean, remaining underwater for long periods of time.
A look at their ships may reveal the highest technological point that a civilization, past or present, has reached.
(the pic is from: http://russwbeck.wordpress.com/)