He also managed to bankrupt the Empire, which led to the collapse of the northern border to the slavic tribes.
I have read people claim (never read stuff on Justinian) that any success was down to other notables around him (eg Belisarios, Theodora etc).
He did have Anthemios and Isidoros build the plan (and carry it out) for the Hagia Sophia, though.
That's Justinian the Great. Justinian II was a separate emperor of the Heraclian dynasty.