I found this tree in Crete, Greece close to the sea, planted next to a building. Since I haven't seen this tree anywhere else in the island, I suppose it was planted by someone. Here are some pictures of it.
Based on the distinctive leaf shape and placement of the fruit along the stem that appears to be a papaya.
If so then the plant should "bleed" latex (a milky white fluid) when damaged. You can test this by breaking off a small piece leaf. Image credit: By Max.kit - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=54547062