California

Natural arches - also known as natural bridges - are formed when relatively soft rock is worn away by the action of tides, rivers or weather erosion, leaving behind a bridge-like structure of harder rock. Although there are thousands around…

On July 11, 1922, the Hollywood Bowl opened. Although less formal performances had been held in this natural amphitheatre for a few years (Wikipedia has a photo of a female duo playing on a stage consisting of a barn door),…

On May 27, 1937, San Francisco's Golden Gate Bridge opened, with around 200,000 people walking or roller-skating across on the first day before it was opened to traffic. Close to a million people visited for the 50th anniversary celebration in…

On May 19, 1743, the first Celsius mercury thermometer design was published by Jean-Pierre Christin. Only a handful of countries still doggedly hold on to the Fahrenheit scale, including the US where the World's Tallest Thermometer is found in Baker,…

On May 16, 1929, the first Academy Awards (Oscars) took place at the Hollywood Roosevelt Hotel. 270 people paid $5 for dinner and the ceremony took all of 15 minutes - a far cry from the bloated excess of the…

We've visited a few solar power generation facilities in the past, but here is a roundup of solar power towers - elevated structures surrounded by movable mirrors called heliostats. The mirrors concentrate solar energy onto receptors in the tower where…