The Red River zoning area runs about 40 km on a northwest-southeast line through the center of the city, from Hong Ha Bridge to Me So Bridge, covering roughly 11,418 hectares across 16 riverside communes and wards.

Bounded by the dikes on either bank, it is projected to hold between 800,000 and 1.2 million residents.

Bridges mark the boundaries of the corridor's three segments. The middle one, from Thang Long Bridge to Thanh Tri Bridge, covers about 4,548 hectares and 541,000 people.

It is designated the "urban living room" and slated for the heaviest redevelopment, with financial services, commerce and innovation clustered around landmark buildings on a new axis running from West Lake to the ancient citadel of Co Loa.

The plan names the 109-story Era Tower the landmark and symbol of that axis.

Renderings from the Hanoi Construction Planning Institute place it on the right bank, set against West Lake.

The plan does not say where the tower would stand, what it would be used for, how big it would be or when it might be built. No height in meters has been released.

A rendering of the Era Tower in the revised 1:5,000 Red River urban zoning plan. Rendering courtesy of the Hanoi Construction Planning Institute

Hanoi's 100-year master plan names the Red River boulevard one of nine growth axes for the capital. The first phase concentrates on the stretch between Hong Ha and Me So bridges.

A later phase would extend the corridor west from Hong Ha Bridge and south from Me So Bridge to the limits of planned urban development.

That would link both banks to southern growth centers including Thuong Tin and Phu Xuyen, and to the Van Giang-Pho Hien-Hung Yen urban chain, through new river crossings on the ring roads.

The city says it will develop the two banks with maximum respect for the natural terrain and preserve flood discharge space under approved flood control and dike plans.

The dossier rules out narrowing the flood corridor or building new dikes inside existing ones.

Hanoi puts the Red River's course through the capital at about 120 km, making the study corridor roughly a third of it.