Google Maps first started as a C++ programme, a general-purpose programming language-based programme, designed by two Danish brothers, Lars and Jens Eilstrup Rasmussen, along with Australians Neil Gordon and Stephen Ma in a small start-up company called "Where 2 Technologies", based in Sydney, N.S.W. Australia in 2003.

It was first designed to be separately downloaded by users, but the company later pitched the idea for a purely Web-based product to Google management, changing the method of distribution.

In October 2004, the company was acquired by "Google Inc." where it transformed into the web application Google Maps.

In the same month, Google acquired "Keyhole", a geospatial data visualization company (with controversial investment from the CIA), whose marquee application suite, 'Earth Viewer', emerged as the highly successful Google Earth application in 2005 while other aspects of its core technology were integrated into Google Maps.

More Info: en.wikipedia.org