Barcelona is one of the most often-visited European cities. Every year it hosts a multitude of congresses, gatherings and exhibitions of all sorts that attract myriad visitors. It is a cosmopolitan city, a worldwide business hub with a vast range of hotels and culture wherever you look. Barcelona offers visitors the chance to stroll through everything from Roman ruins and the mediaeval city to the neighbourhoods featuring Catalan Art Nouveau (Modernisme) with its unique buildings, its city blocks laid on in a grid, its tree-lined streets and its broad avenues. One of the most popular and busiest spots is the Rambla, a boulevard peppered with newsstands, stalls selling pets, birds and flowers, street performers, cafés, restaurants and shops. As you stroll along the Rambla you can gaze upon lovely architecture such as the Palau de la Virreina (Palace of the Viceroy’s Wife), the Boqueria market and the famous Liceu opera house. But a visit to Barcelona would not be complete without a trip to one of the architectural wonders by the world-famous Catalan architect, Antoni Gaudí. The city’s impressive urban beauty is marked by Gaudí’s vision, and the world took note of Gaudí, as reflected by the fact that UNESCO has declared some of his buildings Human Heritage Sites.