What were the tycoons of the late 19th century? and were they ruthless robber barons or as effective captains of industry?

They could be considered both. They used their money to influence local, state and the federal government. Laws were not passed or not enforced that would regulate big business. However, many of the these same men gave large sums of money (philanthropy) to charities. 

The answer is a Ziggurat. Sumerian's built massive stepped towers on which were built temples dedicated to the chief god or goddess of a Sumerian city. One example of an ziggurat is the Marduk ziggurat, of Etemenanki, from ancient Babylon.