Barcelona (English /bɑrsɨˈloʊnə/, Catalan: [bərsəˈɫonə], Spanish: [barθeˈlona]) is the capital of Catalonia and the second largest city in Spain, after Madrid, with a population of 1,620,943 within its administrative limits on a land area of 101.4 km2 (39 sq mi). The urban area of Barcelona extends beyond the administrative city limits with a population of around 4.5 million within an area of 803 km2 (310 sq mi), being the sixth-most populous urban area in the European Union after Paris, London, the Ruhr, Madrid and Milan. About five million people live in the Barcelona metropolitan area. It is also the largest metropolis on the Mediterranean Sea. It is located on the Mediterranean coast between the mouths of the rivers Llobregat and Besòs and is bounded to the west by the Serra de Collserola ridge (512 metres (1,680 ft)).
Mosaic is the art of creating images with an assemblage of small pieces of colored glass, stone, or other materials. It may be a technique of decorative art, an aspect of interior decoration, or of cultural and spiritual significance as in a cathedral. Small pieces, mostly roughly square, of stone or glass of different colors, known as tesserae, (diminutive tessellae), are used to create a pattern or picture.