As-Sahaba Mosque is the oldest mosque built in Eritrea by the first Muslim Migrants when they first arrived in Abyssinia. They built a Mosque so they could pray, and named it As-Sahaba Mosque. Sahaba in Arabic means companions, and that is to imply that al-Sahaba Mosque was built by the companions of Prophet Muhammed who migrated for Mecca to Habsha. That makes this Mosque the first in Africa.
It was reportedly built by companions of the Prophet Muhammad who came here to flee persecution by people in the Hejazi city of Mecca, present-day Saudi Arabia. This historic mosque is located in the eastern edge of the Massawa port. The most important feature of the mosque is that it points towards the Qibla Awwal (first qibla), al-Aqsa in Jerusalem.
It has a very simple structure with a mehrab and a four-stepped minbar. Although the mosque is believed tobe built in the early seventh century during the time of prophet Muhammad, the current structure reflects some features that did not exist several decades later in Islamic architecture, like the minaret and the curved mehrab. The first curved mehrab was installed by Umar bin 'Abdulaziz in Masjid an-Nabawi. The first known minarets in mosques appear in the early 9th century under Abbasid rule, and were not widely used until the 11th century.
The mosque is only a historical remnant and is generally not functional today, though occasionally prayers are offered in the mosque. During these Salahs, people praying do not face Jerusalem but towards Mecca by correcting their direction a little towards the east. The first qibla in Jerusalem is about 3,000km away, while the later and current qibla in Mecca is about 500km. The mosque covers an area of approx 3,100 square meters. The small domed minaret over the minbar is topped with a small star encircled with inside a crescent.
Source : Madain Project