Olive trees in the groves around the Mediterranean Sea are centuries old, with some dated to 2000 years. The olive tree on the island of Brijuni (Brioni), Istria in Croatia, has a radiocarbon dating age of about 1,600 years. It still gives fruit (about 30 kg or 66 lb per year), which is made into olive oil.

An olive tree in west Athens, named "Plato's Olive Tree", is thought to be a remnant of the grove where Plato's Academy was situated, making it an estimated 2,400 years old. The tree comprised a cavernous trunk from which a few branches were still sprouting in 1975, when a traffic accident caused a bus to uproot it. Following that, the trunk was preserved and displayed in the nearby Agricultural University of Athens.

In 2013, it was reported that the remaining part of the trunk was uprooted and stolen, allegedly to serve as firewood. A supposedly older tree, the "Peisistratos Tree", is located by the banks of the Cephisus River, in the municipality of Agioi Anargyroi, and is said to be a remnant of an olive grove that was planted by Athenian tyrant Peisistratos in the sixth century BC. Numerous ancient olive trees also exist near Pelion in Greece. The age of an olive tree in Crete, the Finix Olive, is claimed to be over 2,000 years old. This estimate is based on archaeological evidence around the tree.

The olive tree of Vouves, also in Crete, has an age estimated between 2000 and 4000 years.

More Info: en.wikipedia.org