There is a festival called [Las Fallas] (Les Falles in Valencian) every year in the Mediterranean city of València on 17th March. The preceding year is used to build large papier-mâché and wood structures, several stories high, of generally 3D cartoon-like design, often representing a topical subject of the time, generally mocking those involved using caricatures. These are only finally assembled around 10th March and then they can be seen and judged for various competitions. In the old city, there will often be a multi-storey [falla] every crossroads or so, although they tend to be limited by space, whereas in the modern areas of the city there are fewer fallas but they will be larger. On 17th March, when the competitions are over, the fallas are burnt - they are specifically built to burn quickly with air flows built into them as part of the design.
Each falla is built and designed by its own organisation, generally without outside funding, although the largest falla in the centre of the city, la Plaça del Ajuntament, is paid for by the city council. The tradition comes from the tidying up of carpenters' workshops on St. Joseph's Day, 17th March, the patron saint of carpenters. The rubbish and spare wood was then burnt in pyres in the street and gradually structures were built and the whole idea developed.
Fireworks are also set off during the festival and the days leading up to it - there is the large fireworks display in the centre of the city from the parks of the old river-bed of the Turia which is watched by well over a million on the bridges and surrounding rooftops of the city as well as millions on TV and the Mascletà , fireworks in the centre of the city at 2 pm each day leading up to the 17th, designed purely for sound and often reaching 120 dB, the whole display lasting around 10 minutes.