The Ka`bah is the first and the most ancient house of worship ever built for all mankind and it was dedicated to the worship of one God. So by facing toward the Ka`bah in our prayers, we are stressing the unity of mankind under the Lordship of the One and only God.
Moreover, by facing toward the Ka`bah, we are stressing the concept of Allah, the Almighty being the center of our lives.
From the Qur’an and Hadith we learn that the Ka`bah was the first House established for mankind to worship Allah. Almighty Allah says, (Lo! the first Sanctuary appointed for mankind was that at Mecca, a blessed place, a guidance to the peoples.) (Aal `Imran 3:96) It is not mentioned in any verse of the Qur’an or authentic Hadith that it was built by Adam (peace and blessings be upon him).
Some commentators of the Qur’an say that it was first built by Adam (peace and blessings be upon him) and some others say that it was first built by the angels on this earth. When Prophet Ibrahim (peace and blessings be upon him) arrived at the place of the Ka`bah, the building itself did not exist.
Even the city of Makkah had no inhabitants. Allah showed Prophet Ibrahim the site of the Ka`bah (Al-Hajj 22:26) and then he and his son Isma`il (peace and blessings be upon them both) together raised its foundations and built it from the ground up. (Al-Baqarah 2:127)
The building of the Ka`bah remained after the time of Prophet Ibrahim (peace and blessings be upon him), though it had some structural damage from time to time and underwent repairs. When Prophet Muhammad (peace and blessing be upon him) was about thirty-five years old, before his Prophethood, the Quraish rebuilt the Ka`bah because it had been damaged due to a major flood in Makkah. The Ka`bah today stands on the same foundations on which it was raised by Prophet Ibrahim and his son Isma`il (peace and blessings be upon them).