Tourism in Croatia () is a major industry of country's economy, accounting for almost 20% of Croatia's gross domestic product (GDP) as of 2021. The history of tourism in Croatia dates back to its time as part of Austria-Hungary when wealthy aristocrats would converge to the sea, but had expanded greatly in the 1960s and '70s under the economic policies of the former Yugoslavia. Today, Croatia is one of the most visited tourist destinations in the Mediterranean, with a total of 11.2 million tourists visiting in 2021. Tourism in Croatia is concentrated in the areas along the Adriatic coast and is strongly seasonal, peaking in July and August. Eight areas in the country have been designated national parks, with an additional eleven as nature parks. Currently, there are ten sites in Croatia on the UNESCO List of World Heritage Sites. History Since 2012, the year before Croatia joined the EU, the number of annual tourist arrivals increased by nearly 6 million. Economists argue that Croatia's joining the EU made them a more desirable tourist location due to reinvestment in their economy, more open trade barriers, and lessened customs control. Only 15% of the coast, the main tourist attraction in Croatia, is urbanized, and plans are in progress to gradually develop Croatia's tourism sector more. The Croatian Tourism Development Strategy has a goal to make Croatia a globally recognized tourist destination for all seasons, and is working towards that goal by building more luxury accommodations, including hotels and tourist services, or renovating older ones. Croatia also has one of the UNWTO's Sustainable Tourism Observatories, part of the organization's International Network of Sustainable Tourism Observatories (INSTO). The observatory is considered a commitment to monitoring and building sustainable tourism. Tourist regions The Croatian National Tourist Board has divided Croatia into six distinct tourist regions. Istria The west coast of the peninsula of Istria has several historical towns dating from Roman times, such as the city of Umag, which hosts the yearly Croatia Open ATP tennis tournament on clay courts. The city of Poreč is known for the UNESCO-protected Euphrasian Basilica, which includes 6th-century mosaics depicting Byzantine art. The city plan still shows the ancient Roman Castrum structure with main streets Decumanus and Cardo Maximus still preserved in their original forms. Marafor is a Roman square with two temples attached. One of them, erected in the 1st century, is dedicated to the Roman god