The reason I have chosen the kaa’ba is that it is a very important building, in fact it was the first structure ever built. The building of the kaa’ba represents the time beginning the practice of religions based on worshipping one God only. Before prophet Adam [as] came down to earth, the Angles and all of Allah’s creations prayed towards the direction of kaa’ba in the high heavens. There was even Hajj performed there. When Prophet Adam came down to earth Allah ordered to build the kaa’ba right underneath the spot were angels prayed. Then hundreds of years later when prophet Ibrahim was tested in many ways by Allah and he passed his tests, Allah assigned him the special task of calling people towards him by building the kaa’ba. The Prophet Ibrahim did that along with his young son Ismail. When they were building the kaa’ba they were praying and had pure intentions to accept the kaa’ba and make it a place of worship for Allah alone for all humanity and for all time. Every day millions of Muslims face the kaa’ba to pray and once a year many of them do Hajj around it. Building it was a very important event because if it was not built, Islam would not be the same. How it happened was that prophet Ibrahim built it as the House of God, for the main purpose of worshipping of Allah alone.
The event took place in Saudi Arabia in the city of Mecca many years ago in the time of prophet Ibrahim. As I already mentioned it was first built by Prophet Adam. But was destroyed it had been rebuilt then. Allah had told the Prophets to build it. They had Built what we now pray facing.
What happened during the event was much more than it seems. It was a building very important to build . The outcome was that Muslims can worship Allah towards Kaaba. If Kaaba was not there, then they could do not any Hajj or Salat and if they prayed towards Bait Ul Maqdas (the first Qibla) then how would they call Jews and Christians to the pure worship of Allah?
If none of this happened is in history things would not be the same. Kaaba calls all humanity to the pure worship of Allah and children of Ibrahim (a.s) can come back to this point of unity. Islam would have lost connection with its past prophets and messages so it would impact Islam by making Islam have less worship of Allah and then Muslims can not call people of the book to Islam. There would also be no Hajj or Salat and most of the religious acts in Islam would not be there.