Begun in 1015, Strasbourg's Notre-Dame Cathedral is the fruit of more than 4 centuries of construction. A Gothic masterpiece, it was crowned in 1439 by a 142-metre spire, making it the world's tallest monument until the 19th century. Listed as a historic monument and a UNESCO World Heritage Site, today it welcomes over 4 million visitors a year, and remains one of the most powerful symbols of European heritage.