This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
Q: The 1-mile-long (2 km) Breakwater in Plymouth Sound was designed by John Rennie in order to protect the fleet moving in and out of Devonport; work started in 1812. Numerous technical difficulties and repeated storm damage meant that it was not completed until 1841, twenty years after Rennie's death. In the 1860s, a ring of Palmerston forts was constructed around the outskirts of Devonport, to protect the dockyard from attack from any direction.
A:
In kilometers, how long was the Plymouth Sound Breakwater?