A fine example of early Georgian symmetry and proportion, the facade of this series of townhouses was of pale Portland stone and deep terracotta brick with elliptical arches, neoclassical columns and reed window surrounds. Now, 300 years on, nothing has changed. Apart from one big difference: every single brick and stone of No.1 Grosvenor Square has been completely dismantled, cleaned, restored, numbered and prepared for reassembly in exactly the same order, just like one enormous jigsaw puzzle. Like one giant anniversary secret, it’s currently secretively wrapped up, giving no clue to the extent of the operations in the 1, 55,000sq.ft. Of space within. Almost three centuries after its construction, one of the most prized addresses in London will finally be visible in all its restored glory. Right in the very middle of Mayfair, on the spot of the most coveted square of the board game Monopoly, the location doesn’t get more prestigious than this. Mayfair has remained consistently exclusive since it was first developed in the early 1700s by Sir Richard Grosvenor, heir to the surrounding 100 acres of the West End and forbear of the current Duke of Westminster.

The neighborhood that the nobility loved

Hundreds of years ago, Mayfair Luxury retail is part of the elite neighborhood. Was all meadows and orchards.

As the name suggests, it was the venue for a fair that was held annually in May. It passed to Sir Richard Grosvenor from his father, who had married into money and with it, Belgravia, Mayfair and most of the West End. It was in 1720 that he set about developing it into a fashionable residential address.

Unlike other areas of London where fortunes have fluctuated, Mayfair has remained chic through the centuries. No.1 Grosvenor Square stayed fashionable with the nobility and the glitterati (Irish author and playwright Oscar Wilde lived there, as did several of the characters in his plays and novels).

There’s a strong American connection at Grosvenor Square. John Adams, the second president of the United States, lived there from 1785 to 1789. In 1938, the US Embassy was established at No. 1 itself, and the Square became known as Little America. General Eisenhower set up his military headquarters at No. 20, while No. 23 was used as the US Navy building. Adlai Stevenson died at Grosvenor Square. To encourage presidential aspirations in his son (whose career Stevenson had ironically enabled), Joseph Kennedy turned part of the ground floor into a replica of the Oval Office.

The former embassy is now being converted into a hotel. The £1 bn project, due to be finished in 2023, will become a 137-bedroom property, with five restaurants and a 1000-person capacity ballroom. Readapting to modern times This historic garden square is undergoing a massive transformation.

New building apartments and hotels are under construction. The Grosvenor Estate is rejuvenating the square, while international investors and developers are revamping the buildings. New hotels and restaurants are opening up in the neighbourhood.

Inside No.1 Grosvenor Square

From the outside, the building is now exactly as it would have been in the 18th century with the benefit of modern advantages. Internally, at around four metres, the ceilings are now amongst those of any historic London property. There are some 21st-century twists like the penthouse suite. Occupying the whole of the footprint of the building, it’s constructed to provide a complete 360-degree view that reaches far over the leafy square of the plane and cherry trees, onto Hyde Park and as far as the London Eye and the Shard. And in line with Lodha’s emphasis on privacy, the penthouse will be completely invisible from the exterior.

Rules surrounding listed buildings are inconvenient but are in place to ensure that their integrity is not compromised. It’s not without irony that Eric Parry Architects has gone out of its way to adhere to conditions that should have been imposed to treat the building with the sensitivity that it deserves.

The reception room of some of the apartments benefit from huge sash windows that open onto a view of Grosvenor Square gardens, flooding the beautifully appointed west-facing rooms with morning and late afternoon light. The layout of the apartments is linear so that one room progresses into the other in one grand flow of muted luxury. No expense been spared — from the grand reworking of the structure itself down to the smallest details: bedrooms with their suede-lined wardrobes, kitchens whose marble worktops have been sealed so carefully that you can feel the texture of the ancient stone veins underneath the surface.

The rooms bear the stamp of international design team Yabu Pushelberg, who has complemented the simple elegance of the architectural detail with neutral colours and textured backdrops by Chanel, Hermes and other iconic luxury houses, to enhance the artworks from world-renowned artists.

They'll be in a strong position to augment their series since Lodha works closely with Sotheby’s on exhibitions and events.

Besides the apartments, there are a further 10,000sq.ft. given over to a 25m swimming pool, a vitality pool, clubroom, gym, spa and cinema. Residents will also have 4000sq.ft. of a Michelin-starred restaurant — chef to be announced. The level of service will be five-star without being either intrusive or impersonal, with round-the-clock concierge and valet staff for whom no job will be too big or too small. “Clients want a home, not a hotel. They spend enough time in luxury hotels and want to come back to something meaningful,” says Charles Walsh, a director at Lodha.

And here’s a whimsical touch: as homage to the hard-partying, hard-driving Bentley Boys who lived at Grosvenor Square during the Roaring Twenties, there'll be a Bentley at residents’ disposal for running around town. Not that there’s any need to drive anywhere. Claridge’s, Le Gavroche, the Connaught, the Dorchester and 21 other Michelin-starred restaurants are on the doorstep. The main couture houses are just a stroll down the road. Mount Street, which now commands higher retail rates than Bond Street, is at the heart of the Mayfair Village, a thirty-second walk from the Square. Sotheby’s is in the next street, as are all the main art dealers. Owning a piece of living history.

For Lodha, which undertakes exciting and demanding projects, No.1 Grosvenor Square has been a very interesting project. The whole building was ripe for modification. The Square was built with the nobility in mind in the eighteenth century and it’s hardly surprising that a few things would have to change to bring it up to date. The changes have been simultaneously subtle and drastic. For Eric Parry Architects, which wins awards for restoration projects and ultra-modern designs alike, one of the most complex aspects of the project was the alteration of the ceiling height, which was necessary for the process of returning the building to gracious modern living, suitable for Lodha’s standards of luxury.

Privacy is paramount. Once in residence, owners will have the protection of embassy-level security and state-of-the-art biometric access and laser beams. The layout of the underground car park and drop-off is discreet, which ensures that people can’t be seen getting in and out of their cars. There’s even a secondary escape into an unexpected exit.

Lodha has emphasized the historical aspects of No.1 Grosvenor Square, like the Oval Office replica room, which has been preserved in its entirety to form part of the area used by residents to access their apartments. “People want a piece of history in London,” says Walsh. The apartments are available under leasehold terms of 999 years, which takes posterity well into account: “It’s a bit like a Patek Philippe watch” —a legacy which the company says you don’t own but curate for future generations. It’s part of the enduring nature of their purchase.

We won't be around in 300 years, but the descendants of No.1 Grosvenor Square will be. Permanence is what it’s all about. This is a one-off. Says Walsh, “We'll never build a building like this again.”

A guide to good living in Grosvenor Square

The Royal Academy, five minutes’ walk away on Piccadilly, hosts collections of major artists every two to three months. Lucien Freud’s paintings are currently on view, and Anthony Gormley’s work is due from September this year. You can become a ‘Friend of the Royal Academy’, which entitles you to priority access and private views. Just over the road on the other side of Piccadilly is you rlocal supermarket, Fortnum and Mason’s (well, it’s the ultimate upmarket department store, holding the Royal Warrant). Purveyor of the finest foods, it has its brand of pretty much everything. Have teat Fortnum’s in the elegant early Georgian Tea Salon. The shop has several restaurants and also offers private dining in beautiful surroundings.