A Yemeni visitor walks on a path that leads to the Thula Fort at the historical city of Thula, 45 km north of Sanaa, Yemen, on May 12, 2013. Thula Fort is one of 20 nominees for the 2013 Aga Khan Award for Architecture which is given every three years to projects that set new standards of excellence in architecture, planning practices, historic preservation and landscape architecture, in which Muslims have a significant presence. Thula boasts an impressive collection of stone buildings that date back to the 1st millennium BCE. The Thula fort was threatened by the disruption that might ensue from the construction of a road. However, the Yemeni government has undertaken a series of historic preservation projects to protect cultural assets, including rebuilding the walls of burial grounds, watch towers, paths and waterways, and repairing the cistern that remains in use to this day.(Xinhua/Mohammed Mohammed)

A Yemeni passes an old building at the Thula Fort at the historical city of Thula, 45 km north of Sanaa, Yemen, on May 12, 2013. Thula Fort is one of 20 nominees for the 2013 Aga Khan Award for Architecture which is given every three years to projects that set new standards of excellence in architecture, planning practices, historic preservation and landscape architecture, in which Muslims have a significant presence. Thula boasts an impressive collection of stone buildings that date back to the 1st millennium BCE. The Thula fort was threatened by the disruption that might ensue from the construction of a road. However, the Yemeni government has undertaken a series of historic preservation projects to protect cultural assets, including rebuilding the walls of burial grounds, watch towers, paths and waterways, and repairing the cistern that remains in use to this day.(Xinhua/Mohammed Mohammed)

A Yemeni walks on a path that leads to the Thula Fort at the historical city of Thula, 45 km north of Sanaa, Yemen, on May 12, 2013. Thula Fort is one of 20 nominees for the 2013 Aga Khan Award for Architecture which is given every three years to projects that set new standards of excellence in architecture, planning practices, historic preservation and landscape architecture, in which Muslims have a significant presence. Thula boasts an impressive collection of stone buildings that date back to the 1st millennium BCE. The Thula fort was threatened by the disruption that might ensue from the construction of a road. However, the Yemeni government has undertaken a series of historic preservation projects to protect cultural assets, including rebuilding the walls of burial grounds, watch towers, paths and waterways, and repairing the cistern that remains in use to this day.(Xinhua/Mohammed Mohammed)

Yemeni workers carry substances used in renovating a path that leads to the Thula Fort at the historical city of Thula, 45 km north of Sanaa, Yemen, on May 12, 2013. Thula Fort is one of 20 nominees for the 2013 Aga Khan Award for Architecture which is given every three years to projects that set new standards of excellence in architecture, planning practices, historic preservation and landscape architecture, in which Muslims have a significant presence. Thula boasts an impressive collection of stone buildings that date back to the 1st millennium BCE. The Thula fort was threatened by the disruption that might ensue from the construction of a road. However, the Yemeni government has undertaken a series of historic preservation projects to protect cultural assets, including rebuilding the walls of burial grounds, watch towers, paths and waterways, and repairing the cistern that remains in use to this day.(Xinhua/Mohammed Mohammed)

Yemeni workers repair walks of the Thula Fort at the historical city of Thula, 45 km north of Sanaa, Yemen, on May 12, 2013. Thula Fort is one of 20 nominees for the 2013 Aga Khan Award for Architecture which is given every three years to projects that set new standards of excellence in architecture, planning practices, historic preservation and landscape architecture, in which Muslims have a significant presence. Thula boasts an impressive collection of stone buildings that date back to the 1st millennium BCE. The Thula fort was threatened by the disruption that might ensue from the construction of a road. However, the Yemeni government has undertaken a series of historic preservation projects to protect cultural assets, including rebuilding the walls of burial grounds, watch towers, paths and waterways, and repairing the cistern that remains in use to this day.(Xinhua/Mohammed Mohammed)

A Yemeni visitor looks at a cistern built to save rain water at the Thula Fort at the historical city of Thula, 45 km north of Sanaa, Yemen, on May 12, 2013. Thula Fort is one of 20 nominees for the 2013 Aga Khan Award for Architecture which is given every three years to projects that set new standards of excellence in architecture, planning practices, historic preservation and landscape architecture, in which Muslims have a significant presence. Thula boasts an impressive collection of stone buildings that date back to the 1st millennium BCE. The Thula fort was threatened by the disruption that might ensue from the construction of a road. However, the Yemeni government has undertaken a series of historic preservation projects to protect cultural assets, including rebuilding the walls of burial grounds, watch towers, paths and waterways, and repairing the cistern that remains in use to this day.(Xinhua/Mohammed Mohammed)