That last sentence is awesome: >The massive wood andmetal door slowly swung open to darkness.<
>They could still hear the noises of the street. The horses whinnying. The creaking of the carriage harness. The hiss ofthe gas lights. <
I suggest stringing these sentence fragments together into a complete sentence. Fragments make choppy reading, although they can be effective in fast-paced action scenes.
Here, I think a complete sentence would work better.
They could still hear the the horses whinnying in the street, the creaking of the carriage harness and the hiss of the gas lights.
Or, if you want more dramatic punctuation, try a colon:
They could still hear the noises of the street: the horses whinnying, the creaking of the carriage harness,the hiss ofthe gas lights.
I hope this helps.