The capital city of Yemen, Sana'a is one of the oldest populated cities in the world. Historically, its strategic location has allowed it to control the movement of trading networks, governing access from the Indian Ocean and Mediterranean to the Red Sea ports. Sana'a has been a site rich in Islamic architectural history since the seventh century, when Islam was largely adopted in Yemen. Sana'a's architectural heritage is a culmination of influences and styles; containing elements of Umayyad, Rasulid, and Ottoman architecture. Particular to Sana'a is a vibrant tradition of vernacular architecture, known for its use of carved timber, stone, and stepped masonry in multi-level houses. The western city has historically been the site of palatial architecture, including the notable Ayyubid "Sultan's Garden." Other notable complexes include a number of caravanserais and public hammams. In 1974, legislation required that all new buildings be executed in accordance with the traditional Yemeni styles. In 1986, the old city was declared a UNESCO World Heritage Site. Much of the Old City has since been destroyed, as a result of bombings throughout 2015.
Ali, Hikmat H., Imad A. al-Hashimi and Fua'ad al-Samman. "Investigating the Applicability of Sustainable Urban Form and Design to Traditional Cities, Case Study: The Old City of Sana'a." Archnet-IJAR: International Journal of Architectural Research. 12, 2 (2018): 57-80.
This research compared the traditional urban form of old Sana'a with the modern by applying three main basic principles of sustainability; 1. Form and density, 2. Walkability and connectivity and 3. Building energy. The method of inquiry was based on qualitative and quantitative methods and analysis using GIS, ECOTECT and Space Syntax modelling. The findings show that traditional form with its higher building density and compactness is a good model with regards to sustainable principles. Similarly, as to walkability index, traditional layout has higher rates of intersections and connected nodes and least angular changes with higher rates of integrations and choices in terms of Space Syntax properties than new layouts. Finally, the result of applying ECOTECT for urban solar analysis to confirm that the traditional pattern achieved sufficient values of solar access, exposure and shadows over different periods of the year. The overall results indicate that the traditional urban layout is more sustainable in terms of form and density, walkability and connectivity and urban solar energy than the new layouts.