The Neapolitan Sixth chord is commonly used in first inversion. The next example from Chopin's Prelude #20 shows the chord in root position. The key is C minor, so the Neapolitan sixth chord is Db major.
Sometimes the Neapolitan sixth chord is followed by an auxiliary diminished seventh chord of the V degree. Bach's G minor choral Ach Gott, vom Himmel sieh' darein offers a good example:
The following excerpt is from the Andante of Mozart's Concerto K 488. Click the measure were you find the Neapolitan sixth chord. The Neapolitan sixth chord appears in two measures, can you find those measures? Ask yourself, if the key of the piece is F# minor, what major chord is half-step above? You will probably find the chord in first inversion:
Click the measures where you see a Neapolitan sixths...