The Louvre is probably the most famous of all art galleries in the world - whilst the Guggenheim is the most widespread. Between them they house some of the finest art from Ancient Egypt to the present day.
The Louvre, in Paris, was originally a fortress, built in the 12th century. It was converted into a royal residence 400 years later and was decorated with many great artworks such as The Mona Lisa.
Following the French Revolution the Louvre became a museum, opening its doors in 1793. Over the following centuries its collection has grown, helped in part by the conquests of Napoleon.
It has many collections devoted to antiquities from different areas (for example Islamic Art) and others to differing arenas, such as sculpture, decorative arts, painting, prints and drawings.
The Solomon R Guggenheim Foundation was set up in 1937 by the philanthropist with whom it shares its name. Its mission is to "promote the understanding and appreciation of art, architecture, and other manifestations of visual culture, primarily of the modern and contemporary periods".
The oldest museum established by the foundation is the Solomon R Guggenheim Museum in New York, which opened in 1939. Others followed in Venice, Manhattan, Bilbao, Las Vegas, Mexico, Berlin and Lithuania. Sadly, only three of these remain open today (New York, Venice and Bilbao) though others are planned for Abu Dhabi and Helsinki.