The Kaba was allegedly built by prophet Ibrahim with his son Ismail. The actual date of when it was originally built is unknown however, it is common knowledge that the Kaba has been destroyed and rebuilt many times.
So there is no doubt that the current Kaba is not the original.
Another artist drawing of the Kaba before it became a very lucrative business for the area. This is an artists depiction of the Kaba during the time of the prophet. It is noticeably different to the current one as it is not etectangular.