If you take a look at it, you'd realize it is tall, and far from any habitation. And in a military base. If is was attacked, there would be little risks of civilian collateral damages. Sure, it is in central Tel Aviv on paper, but more because the city grew around it than because it was deliberately put there.
I couldn't find anything about the Greek army HQ, care to provide a link?
For what reason do you think they'd build their HQ there and not far away from the population?