My office building dates back to the 1890s, so if walls count, that's it. I can't identify any contents that go back further than the 1970s, if that. At home, in the right room, I can spot human products dating back about 7,000 years and natural products that go back a few hundred million.

And beautiful as the Uffington horse certainly is, I wouldn't date it later than ate La Tene, around 100 BCE or so.