In this poem, Wordsworth's speaker stands on Westminster Bridge in the very early morning and views London. What strikes them most profoundly is the stillness and serenity of the city spread out in the sunrise. Unlike later in the day, when it will be full of traffic, crowds, and activity, right now London is lovely in its quiet. The speaker says, filled with emotion,

Ne'er saw I, never felt, a calm so deep!

The "mighty heart" of the city, they go on to say, is "lying still."

Romanticism, unlike realism, endeavors to show the world in a positive light. This poem is a Romantic treatment of London because it depicts the city at a lovely moment. Beneath the dirt, crime, and poverty of the city is a beautiful, calm heart, a soul in repose.

The treatment is Romantic, too, because the speaker responds emotionally to the early morning scene laid out before them as they view it in the hazy glow from the bridge. The exclamation mark in the quote above testifies to the speaker's heart being overwhelmed by the deep calm they see. The speaker says the "soul" that could pass by this scene without being moved would be "dull," because the vista is "touching in its majesty."

The Romantics exalted nature, and the speaker here connects the city to nature, stressing the air, the sun, the light, and the open fields around it. In this setting, London becomes for a brief moment before it awakes, part of a serene natural environment.

In his poem titled “Composed upon Westminster Bridge, Sept. 3, 1802,” William Wordsworth writes in a Romantic mode about the “mighty heart” of the City of London. He does so in a number of ways, including the following:

• In line 1, the speaker immediately mentions “Earth” – a fact that already helps suggest that this may be a “Romantic” poem. Whereas poets of earlier centuries often emphasized God, heaven, and the afterlife, the Romantics tended to be concerned with the visible world before them. The brief reference to God at the very end of this poem might almost seem perfunctory; certainly Christian themes are not stressed in this work as they might have been in a poem written, say, in the sixteenth or seventeenth century.
• In the rest of line 1, the speaker shows enthusiasm for beauty – another common feature of Romantic poetry.
• In line 2, the speaker posits the existence of persons whose souls are “Dull” – persons precisely the opposite of the Romantic, with their heightened sensitivity to anything sublime or lofty. A typical Romantic focus of sublimity is in fact explicitly stated when the speaker refers, in line 3, to London as

    A sight so touching in its majesty . . . [emphasis added]

• Line 5 is typically Romantic in is double emphasis on beauty and on the calm quiet of the morning. London, in other words, is at this time of day not only beautiful but also peaceful – a trait greatly admired by the Romantics.
• Line 7 is typically Romantic in its stress on the beauty of nature, particularly the kind of nature associated with the countryside. Subsequent lines also emphasize the sheer visual beauty of nature.
• Line 8 is Romantic in its emphasis on air that is “smokeless” and thus untainted by the kind of ugliness often produced by humans living in large cities.
• Of particular interest, from a Romantic perspective, is line 12:

The river glideth at his own sweet will . . .

This line not only emphasizes the beauty of nature untrammeled by human interferences (such as locks and dams), but it also implicitly celebrates one of the most important of all Romantic values: freedom. Just as the river flows freely, so Wordsworth and other Romantics wished that human beings could live freely.

• The reference in line 14 to London’s “mighty heart” can be seen as typically Romantic in its generous assessment of the citizens of London. If we think of them as the “mighty heart” of the city who are “lying still” before they awake and begin their busy days, then Wordsworth is writing with the kind of cheerful optimism we often associate with the Romantics. He is not mocking or satirizing London or its citizens here, as a poet of a hundred years earlier might have done. Instead, he is celebrating London as the heart of England – looking for the positive and finding it, as the Romantics often did. Wordsworth here also personifies London, treating it as if it were a living thing – thus reflecting the common tendency among the Romantics to use the so-called “pathetic fallacy” of treating inanimate things as if they were human beings.
• Finally, the speaker feels inspired by the beauty he sees before him and re-creates that beauty for us, so that we might feel inspired and awe-struck as he is -- a typical Romantic purpose for writing a poem.

In all these ways, the, Wordsworth extols London in fashions that seem typical of a Romantic writer.