Long (length)

[poli]

How would you say: The Great Wall of China is a thousand miles long>
¿La gran muralla de China tiene una largura de mil millas?
...es un mil millas largo?
...lleva mil millas?

[Perikles]

How would you say: The Great Wall of China is a thousand miles long>
¿La gran muralla de China tiene una largura de mil millas?
...es un mil millas largo?
...lleva mil millas?...tiene mil millas de largo

[aleCcowaN]

¡Exactamente!

La Gran Muralla China (o simplemente "la Gran Muralla") tiene más de mil leguas de largo.

[micho]

How would you say: The Great Wall of China is a thousand miles long>
¿La gran muralla de China tiene una largura de mil millas?
...es un mil millas largo?
...lleva mil millas?

Para mi la traducción puede ser: La Gran Muralla China tiene una longitud de mil millas, o, tiene mil millas de largo (As Perikles said). La longitud de la Gran Muralla China es de mil millas. La Gran Muralla China mide mil millas.
Elige la que mas te guste o mejor vaya en el contexto.

[Don José]

I would have said "largura" it is not a Spanish word, but curiously it is in the DRAE. Now that I think about it, I think it is often used for clothes and perhaps in other contexts. However, I wouldn't use it for the Great Wall.

[aleCcowaN]

Largura, largueza and largor. I have to confess that hearing people speaking of el largor y el anchor of something sounds to me like a piece of chalk screeching on a blackboard, but it's real Spanish. Largo y ancho. Largor y anchor. Largura y anchura. Largueza y ancheza.

[poli]

Thank you for the largesse of your answers.