I think it is remarkable that nobody mentioned André Weil's *Basic Number Theory* until now. André Weil made both marvellous contributions to harmonic analysis on locally compact Abelian groups and to number theory.

In *Basic Number Theory*, familiarity with number theory is not a prerequisite. However, the reader is expected to be familiar with the basic theory of locally compact Abelian groups and the Haar measure on such groups since these methods are extensively used to prove results in number theory. I think this approach is non-standard, but it beautifully shows the application of harmonic analysis to number theory.