What was the area of the first mosque built by the Prophet, peace and blessings be upon him, and did it have a mihrab?

The first mosque built by the Prophet, peace and blessings be upon him, was Quba Mosque in Medina. He founded it upon his arrival in Quba, among Banu Amr ibn Awf, and he stayed with them for fourteen nights.

Muslims have shown great care for Quba Mosque throughout the ages. It was renovated by Uthman ibn Affan, then by Umar ibn Abd al-Aziz, and subsequent caliphs continued to expand and renovate it until the last expansion in 1406 AH. The prayer area alone reached 5035 square meters, with a total area of 13500 square meters.

Hadiths have been narrated that illustrate the virtue of praying in it, including that the Prophet, peace and blessings be upon him, used to visit it every Saturday, walking or riding, and pray two rak'ahs therein. And that praying in it is equivalent to performing Umrah.

As for mihrabs, they were not present in Quba Mosque when it was built. Their use in mosques began in the second century AH.