Aesculus hippocastanum

Horse Chestnut.

We are used to see this tree in parks and gardens, along streets.... What is worth noting however is that in the wilderness it is nearly extinct. There are, as far as I know, only two small areas where it still grows natively: one in Greece and one in my country, Bulgaria, located to the north of the easternmost end of the Balkan Mountain range. So could be said that the Balkans are its homeland.
I wouldn't say it's endangered. No. It grows in our cities throughout the northern hemisphere. Only its native populations are. This is why it was picked as symbol of one of Bulgaria's largest non-governmental conservationist organizations, The Green Balkans.

Another interesting fact is that it is a tertiary relict species.