In this poem, Wordsworth is (unusually for him) talking about how beautiful the city is. He usually contrasts cities and nature, but now he is comparing them. He is using images from nature to say that the city (at least early in the morning) is beautiful.
One image he uses is where he compares the city to the valleys, rocks, and hills. He is saying that the city is just as lovely as any natural scene.
A second image he uses is in the last line where he says the city has a heart -- it is a living, natural being.
The beauty of the morning; silent, bare
Ships, towers, domes, theatres, and temples lieOpen unto the fields, and to the sky
Never did sun more beautifully steepIn his first splendour, valley, rock, or hill;Ne'er saw I, never felt, a calm so deep!The river glideth at his own sweet will