Final answer:
The Mali Empire, particularly the city of Timbuktu, is renowned as the center of learning in Africa's second civilization, with its educational institutions becoming highly esteemed in medieval West Africa.
Step-by-step explanation:
The empire in Africa's second civilization most noted for its center of learning is the Mali Empire. The city of Timbuktu became a leading Islamic center for education during the Mali Empire's peak, under the rule of Mansu Musa, who was known for his lavish wealth displayed during his pilgrimage to Mecca. This center of learning attracted scholars from across the Islamic world and became synonymous with knowledge and learning in medieval West Africa. Moreover, later in the 15th century, under the Songhai Empire, Timbuktu continued to be an important educational hub.