Earth hath not anything to show more fair:
Dull would he be of soul who could pass by
A sight so touching in its majesty:
This City now doth, like a garment, wear
The beauty of the morning; silent, bare,
Ships, towers, domes, theatres and temples lie
Open unto the fields, and to the sky;
All bright and glittering in the smokeless air.
Never did sun more beautifully steep
In his first splendor, valley, rock, or hill;
Ne'er saw I, never felt, a calm so deep!
The river glideth at his own sweet will:
Dear God! The very houses seem asleep;
And all that mighty heart is lying still!
The river is more in its natural state. It is not yet being churned and forcibly moved against its will by the work day’s boats and commercial fishing. 
 The river is  personified  as having a free will. The word ‘glideth’ is  onomatopoeic , with its smooth, soft ‘l’ and elongated vowel . We must assume that Londoners hadn’t yet dumped the contents of their chamber  pots into The Thames. 
 Yet, the poet chose to see the City as romantic. The archaism ‘glideth’ reinforces this. 
 Note that, in an  inter-textual  reference, this line was adopted by TS Eliot in his poem  The Waste Land .
Composed upon Westminster Bridge September 3 1802