Let me start by saying that Kostas and his sisters' place was beautiful, clean, modern and impeccably well-kept. The location in Monastiraki was a perfect spot in a hip neighborhood that was still steps away to the famed ancient gems Athens is famous for. But the real gem is Kostas himself. He is a very gregarious, affable host who is encyclopedic about the city and Greece in general. He's fluent in English. He was constantly available to answer all our questions about things like where to do laundry, etc. but also with helping us find information on ferry and train tix. His restaurant recommendations were top-notch and local — and this coming from someone highly opinionated about that sort of thing. I cannot recommend Kostas and his place enough! If you're going to Athens and want a mix of cool/off the path while near all the things to see, you would be doing yourself a disservice if you didn't consider this place run by Kostas and his lovely sister.