Culturally, the Mamluk period is known mainly for its achievements in historical writing and in architecture and for an abortive attempt at socio-religious reform. Mamluk historians were prolific chroniclers, biographers, and encyclopaedists; they were not strikingly original, with the exception of Ibn Khaldūn, whose formative and creative years were spent outside Mamluk territory in the Maghrib (North Africa). As builders of religious edifices—mosques, schools, monasteries and, above all, tombs—the Mamluks endowed Cairo with some of its most impressive monuments, many of which are still standing; the Mamluk tomb-mosques can be recognized by stone domes whose massiveness is offset by geometrical carvings.