Mainframes

Mainframes (often colloquially referred to as big iron) are huge and expensive computers used mainly by government institutions and large companies for mission critical applications, usually bulk data processing such as censuses, industry/consumer statistics, ERP, and financial transaction processing.
The term originated during the early 1970s with the introduction of smaller, fewer complex computers such as the DEC PDP-8 and PDP-11 series, which became known as minicomputers or just minis. The industry/users then coined the term "mainframe" to describe bigger, earlier types (previously known simply as "computers").

Lighthouse of Alexandria

The Pharos of Alexandria was a big tower built in the 3rd century BC (between 285 and 247 BC) on the island of Pharos in Alexandria, Egypt to give out as that port's landmark, and later, its lighthouse.

With a height variously estimated at between 115 and 150 meters (383 - 450 ft) it was among the tallest man-made structures on Earth for many centuries, and was recognized as one of the Seven Wonders of the World by Antipater of Sidon. It was the third tallest building after the two Great Pyramids (of Khufu and Khafra) for its whole life. Some scientists approximate a much taller height exceeding 180 metres that would make the tower the tallest building up to the 14th century.