Wolfgang Amadeus Mozart's Piano Sonata No. 1 in C major, K. 279 / 189d (1774), is a piano sonata in three movements. It was written down, except for the first part of the opening movement, during the visit Mozart paid to Munich for the production of La finta giardiniera from late 1774 to the beginning of the following March. A typical performance of the sonata takes about 14 minutes. It is the first of his 18 piano sonatas. All but two of the sonatas, No. 8 in A minor and No. 14 in C minor, are in a major key. Also, the first six sonatas seem to follow the cycle of fifths, to the flat side first and then to the sharp side.
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