Jawatha Mosque 2.82

Jawatha Mosque is located in the village of Al-Kilabiyah, about 12km northeast of Hofuf, Al-Ahsa, Saudi Arabia. It was the earliest mosque built in east Arabia and most of the original structure is in ruins. The site is still used for prayer.
It was built the in seventh year of hijra at the hands of the Bani Abd al-Qays tribe which lived there before and early in the Islamic period. This mosque is believed to be the first mosque built in Eastern Province and is where the second Friday congregation prayer in Islam was offered, the first being held at the Prophet's Mosque in Medina. According to legend, when the Hajr Al Aswad, was stolen from Mecca by the Qarmatians, it was kept in this mosque for nearly 22 years.
Most of the mosque's original structure has been lost and it remains in danger of collapse. Only five small mud-brick arches remain. The visible ruins probably date from around the 9th century AD.