Composers became interested in the music of the waltz. Weber wrote a piece called 'Invitation to the Dance'. It has a main tune, then a set of variations, and at the end it comes back to the first tune. This form became a common way of writing a group of waltzes. Two composers in Vienna who became well known for their waltzes were Joseph Lanner (1801–1843) and Johann Strauss (1804–1849), but the most famous of all was one of Strauss’s sons, also called Johann. Father and son are sometimes called Johann Strauss I and Johann Strauss II. The son is often called the 'King of the Waltz'. He wrote many waltzes which are still very popular today. On New Year’s Day the Vienna Philharmonic Orchestra always give a concert which can be seen worldwide on television. They play lots of Strauss waltzes. The most famous one is called 'The Blue Danube' (German: 'An den schönen, blauen Donau').