Question

1. The boy is ten years old.
2. He is a ten-year-old boy.

3. The building is ten meters tall.
4. The building is ten meters high.

5. It is a ten-meter-tall building.
6. It is a ten-meter-high builing.
7. It is a ten-meter building.
(Which ones are grammatical?)

Answer 1

They all are correct. Seven could also mean it's ten meters wide or deep, not necessarily tall, though. It's not specific as the others are.