The Astrolabe is of interest in showing how much the ancient world knew of astronomy:
And I don’t think we can talk about Ancient Greek Astronomy without considering the Antikythera (around 2nd Century BC):
http://www.antikythera-mechanism.gr/
Although the later probably not really related to ancient astronomy – its still pretty interesting how they applied what they knew.
Here is a recent article published today as a free download on Nature about the Antikythera