Plot real and imaginary parts over the complex plane:
View on the branch cut along the imaginary axis:
Plot curves of vanishing real and imaginary parts of
RiemannSiegelZ:
A version of the Riemann hypothesis requires the limit of

as

to vanish:
Plot double logarithmically the value of the integral:
Calculate a "signal power" of the Riemann zeta function along the critical line:
Plot the difference to the asymptotic value: