I'm reading a book called Dickens' London and in it it talks about the beginning of sidewalks in London. I'm on my phone now but I'll grab the source and quote in a short bit. IIRC, early to mid 1800s l.

Of course you have places like Pompeii which had a sidewalk of sorts mostly to let rain pass through as well as carts.

edit: found it.

Author of 1860s novel Castle Richmond, Anthony Trollope "uses 'pavement' to mean the road, not the area designated for pedestrians. By the time he was writing, the segregation of the two areas was complete, but it was a relatively recent innovation. In 1800s, a memoirist recalled how in the previous century 'the broad flagging on each side of the streets was not universally adopted, and stone posts were in fashion to prevent the annoyance of the carriages.' Within a decade Louis Simond, freshly arrived from America, noticed 'The elevated pavement on each side of the streets full of walkers', keeping them 'out of reach of carriages', the phrasing suggesting that the idea was new to him. The reports of other visitors agree that at this early stage segregated spaces for pedestrians may have been unusual even in London. In 1824, the American clergyman Nathaniel Wheaton described coaches pulling up 'in the throng of foot passengers', the drivers giving warning to pedestrians by an 'accustomed heigh! in a tone so sharp, as to put the most heedless on their guard'. Even in 1835 a guidebook still felt the need to explain to its readers that streets were 'divided into a carriage-way and a foot-path...finished with a kirb [sic] raised a few inches above the carriage-way'. Separate provision for pedestrians arrived fully only with macadam. Earlier paving methods had created kennels, or gutters, down the centre of each street, leaving the dry areas on either side to be used by all."

Macadam was an early form of ashphalt. London also experimented with wooden blocks on the road, which is fascinating to me. Didn't last that long as one would think.

Hope that helps.f

Flanders, J. The Victorian City: Everyday Life in Dickens' London. (2012).