Grosvenor Square is one of London's older squares, dating as far back as 1695, the year it was laid out. That it must have progressed swiftly is evidenced by Pope's reference to it whilst writing from Bristol to Martha Blount in 1716 about the sights of Bristol, when he said "nothing is fine in it but the Square, which is larger than Grosvenor Square."
But it was still probably some years before the square became fashionable, as there is no mention of it in, for instance, the Diary of Lady Cowper (1714—20), who would probably have mentioned it had it become one of the then restricted localities favoured by the ton.
The Square was formed by Sir Richard Grosvenor, a grand builder of that time – indeed, "as great a builder as the Duke of Bedford" - who is also remembered as having acted as cup-bearer at the Coronation of George II.
The actual completion of the Square did not happen until 1725, when Sir Richard summoned his intending tenants to a "splendid entertainment," at which the new streets and squares were solemnly named.
The original site of Grosvenor Square is not without its historical importance. Here, on the approach of Charles after Edgehill in 1641, the rebel citizens threw up a redoubt known as Oliver's Mount, from which the current Mount Street takes its name. The actual site of this fortification was the same space that came to be occupied by the central gardens of the Square.