The distinctive cityscape of Valencia harmoniously blends centuries of architecture. The first stone of Valencia Cathedral was laid in 1262, and one of the chapels holds a chalice purported to be the true Holy Grail. Meanwhile, the Plaza del Mercado provides a delightful contrast between the art nouveau Mercado Central and the Gothic architecture of Lonja de la Seda, a former silk exchange and UNESCO World Heritage site. Moving into the 21st century, the City of Arts and Sciences was designed by renowned Valencian architect Santiago Calatrava and opened in 2005. The soaring arches and gleaming glass of the modern structures host the largest aquarium in Europe, the tallest opera house in the world and other museums. Additional treasures can be found north of town in the Lladró Porcelain Museum. Valencia also has a lovely beachfront promenade, a great place to sample paella in the city where the dish was invented.