whatstheoldbilding intheworlid?

Answer 1

It all depends on what you mean by "oldest building". Here are three possible ways of answering:

1) The oldest building still standing and in use = the Pantheon in Rome.

Originally erected in 27 B.C., the CURRENT structure was built by Hadrian ca. AD 125. Thus it has been standing (and in continuous use!) for nearly 19 centuries!
http://www.lifeinitaly.com/tourism/lazio/pantheon.asp
http://en.wikipedia.org/wiki/Pantheon,_Rome

(The Parthenon in Athens Greece actually stood in tact longer -- from the mid-5th century BC until September 28, 1687, when an Ottoman ammunition dump inside the building, ignited by Venetian bombardment, sverely damaged the structure. But it no longer qualifies.
http://en.wikipedia.org/wiki/Parthenon )
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2) The oldest building discovered by archaeologists and still somewhat intact

The best answer for this may change over time with new discoveries or corrections in dating, but the main structures vying at this time all date from the 4th millennium BC. Here are three sets (beginning with what appears to be the oldest)

a) several temples on the Maltese islands date from 3000 - 3600 BC (the "megalithitc period")
The one most often noted is Hagar Qim on the island of Malta, dating from about 3000 BC
http://www.walkabouttravelgear.com/hagar.htmca. 3000 BC
http://en.wikipedia.org/wiki/%C4%A6a%C4%A1ar_Qim
http://www.art-and-archaeology.com/malta/hagarqim.html

But the Ggantija temples on the island of Gozo are now dated earlier, the oldest one as early as 3600 BC
http://www.aboutmalta.com/gozo/ggantija.html
http://en.wikipedia.org/wiki/%C4%A0gantija

(These are also the oldest religious structures, several centuries before Stonehenge and the Great Pyramid)

b) Irish passage tombs in County Meath (also megalithic)
Most noted: Newgrange and Knowth
http://en.wikipedia.org/wiki/Newgrange
http://mythicalireland.com/ancientsites/knowth/index.html

c) temple in the ancient Sumerian city of Uruk, southern Mesopotamia - from about 3500 BC
http://proteus.brown.edu/mesopotamianarchaeology/699

Mesopotamian studies, incidentally, provide an example of further study leading to CHANGES in dating. The following Time magazine article from 1924 tells of a temple in Ur thought at that time to date back to the mid 5th millennium BC, but NOW dated ca. 2500 BC (see second link)
http://www.time.com/time/magazine/article/0,9171,717865,00.html
http://proteus.brown.edu/mesopotamianarchaeology/799
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3) Perhaps you want ANY evidence of ancient buildings? In that case, some believe they have found a few remnants of VERY old structures

a) Terra Mata in France -- some have argued that they have evidence of structures from the paleolithic -- 380,000 years ago!
http://archaeology.about.com/od/tterms/g/terraamata.htm
http://www.mnsu.edu/emuseum/archaeology/sites/europe/terraamata.html

But there is much debate about the evidence, and whether it truly points to buildings -
http://en.wikipedia.org/wiki/Terra_Amata

b) Time magazine, in March 2000, announced that
"Japanese archaeologists have uncovered the remains of what is believed to be the world's oldest artificial structure, on a hillside at Chichibu, north of Tokyo." They date the remains -- what they say "appear to be 10 post holes, forming two irregular pentagons which may be the remains of two huts"-- to 500,000 yearas ago. (Original report in New Scientist)
http://news.bbc.co.uk/1/hi/sci/tech/662794.stm

I have not heard more about this, and whether similar questions to those about Terra Mata have been raised.

But in any case, in NEITHER of these cases is there anything like a real "building" or any part of one standing now.

Answer 2

Ihopeyoudon'tmeantheoldeststillstanding!
The oldest know city to be excavated is in what is now Iraq and is called Uruk, from about 3500 B.C., biblically known as Erech.
There's lots more at my source site, which is safe... under building