North Africa, far western Asia (Turkey) and southeastern and southwestern Europe.
"Euphorbia characias is an upright euphorbia that is native to Southern Europe, the Balkans and Turkey. It typically grows on erect, woody-based, green stems to 3-4' tall and to 3' wide. Narrow, linear to obovate, blue-green leaves (to 5" long) are spirally arranged along the stems. Each stem is topped in spring by a thick, bottlebrush-like inflorescense of greenish-yellow flowers. " (Missouri Botanical Garden)
Note, that the cultivar, Euphorbia characias subsp wulfenii, tops out at 2′ or 3′ feet with a spread of about 2′ feet."
Some history as an ornamental, listed in Western Garden Book and there is an ornamental subspecies on the Missouri Botanical Garden website.