Select the correct answer. Read this excerpt from Arthur Conan Doyle’s The Adventures of Sherlock Holmes:

We had reached the same crowded thoroughfare in which we had found ourselves in the morning. Our cabs were dismissed, and, following the guidance of Mr. Merryweather, we passed down a narrow passage and through a side door, which he opened for us. Within there was a small corridor, which ended in a very massive iron gate. This also was opened, and led down a flight of winding stone steps, which terminated at another formidable gate. Mr. Merryweather stopped to light a lantern, and then conducted us down a dark, earth-smelling passage, and so, after opening a third door, into a huge vault or cellar, which was piled all round with crates and massive boxes.

What does the author mostly reveal about the setting?