Gobleki Tepe. (photo via Wikipedia)
Located in Turkey, this is the oldest known religious structure in the world, dating back to around 9000 BCE (so some quick math puts it at roughly 11,000 years old).
Thus, the structures not only predate pottery, metallurgy, and the invention of writing or the wheel; they were built before the so-called Neolithic Revolution, i.e., the beginning of agriculture and animal husbandry around 9000 BC. But the construction of Göbekli Tepe implies organisation of an order of complexity not hitherto associated with Paleolithic, PPNA, or PPNB societies. The archaeologists estimate that up to 500 persons were required to extract the heavy pillars from local quarries and move them 100–500 meters (330–1,640 ft) to the site. The pillars weigh 10–20 metric tons (10–20 long tons; 11–22 short tons); with one found still in its quarry weighing 50 tons. It is generally believed that an elite class of religious leaders supervised the work and later controlled whatever ceremonies took place here. If so, this would be the oldest known evidence for a priestly caste—much earlier than such social distinctions developed elsewhere in the Near East.
There’s a great article in the New Yorker (subscription required) where Elif Batuman travels to Urfa, where Gobekli Tefe is and supposedly the birthplace of Abraham:
Urfa is in southeastern Anatolia, about thirty-miles south of the Syrian border. Tens of thousands of people come here to visit a cave where where Abraham may have been born and a fishpond marking the site of the pyre where he was almost burned up by Nimrod, except God transforme the fire into water and the coals into fish. According to another local legend God sent a swarm of mosquitos to torment Nimrod, and a mosquito flew up Nimrod’s nose an started chewing on his brain. Nimrod ordered his men to beat his head with wooden mallets, shouting, “Vur ha, vur ha!" ("Hit me, Hit me!"), and that’s how his city came to be called Urfa.