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The Kaʿbah is a cube-shaped sacred structure, and according to one explanation, its name is related to this cubical form. It is built with strong stones. Its height is mentioned as 15 metres. Its side from the direction of al-Multazam is 12.84 metres, while its side from the direction of Ḥijr Ismāʿīl is 11.28 metres. The distance between al-Rukn al-Yamānī and the side of the Ḥijr is 12.11 metres, and the distance between al-Rukn al-Yamānī and al-Rukn al-Shāmī is 11.52 metres. The wall rising above the roof of the Kaʿbah is about 80 cm, while the lower threshold is 45 cm, and the raised corner above the threshold is 13 cm. These measurements are cited in Al Jazeera’s encyclopaedic entry on the Kaʿbah.

As for the second part of the question, Prophet Ibrāhīm عليه السلام and his son Prophet Ismāʿīl عليه السلام raised the sacred foundations of the Kaʿbah by the command of Allah. The Qur’an states:

“And remember when Ibrāhīm and Ismāʿīl were raising the foundations of the House…”
(Sūrah al-Baqarah 2:127)

However, the present structure is not exactly the same physical building as it stood in the time of Ibrāhīm عليه السلام. The Kaʿbah has undergone several reconstructions and restorations throughout history, including the reconstruction by Quraysh before the prophethood of the Prophet Muhammad ﷺ, the rebuilding by ʿAbdullāh ibn al-Zubayr رضي الله عنه, later reconstruction under the Umayyads, and major restorations in later periods.

Ibrāhīm عليه السلام built the Kaʿbah upon its sacred foundations, but the present structure is the result of later historical reconstructions and restorations. 

For more details, kindly read:
https://en.islamonweb.net/kaba