When was the Prophet's Mosque built and how was it built?

The first act performed by the Prophet, peace and blessings be upon him, upon his arrival in Medina was the construction of his noble mosque in the place where his she-camel knelt, which the Prophet, peace and blessings be upon him, purchased from two orphans. The construction of the mosque began in Rabi' al-Awwal of the first year of the Hijra, and the Prophet, peace and blessings be upon him, participated in the work himself. Its walls were built with bricks and mud, its roof from palm fronds, its pillars from tree trunks, and its floor was covered with sand and pebbles. It had three doors.