Robert De Niro gained 60lb to play the middleweight boxing champion Jake LaMotta in Raging Bull; paid a dentist $5,000 to grind down his teeth for the role of the convicted rapist Max Cady in Cape Fear (then spent $20,000 after the wrap party to have them corrected) and worked as a cabbie for three months for his role as Travis Bickle in Taxi Driver.

Doing things by halves isn’t the De Niro way. Which is why his latest project is rather interesting - he’s just become a method hotelier.

Details of his New York boutique have been kept under wraps since the planning application was lodged seven years ago. Several postponed opening dates since 2006 have only reinforced the hype, but, finally, the Greenwich Hotel, in the downtown, increasingly gentrified TriBeCa district, welcomes its first guests this month (with the grand opening in May). So, off we went for a preview.

Like De Niro’s best roles, it is a study in obsessional detail and subtle presentation. The meticulous approach runs from the bottom up. Each of the hundreds of thousands of bricks in this new-build has been handcrafted to one of 20 specifications by the only company in the USA that caters for such perfectionism. The aim was to achieve a crumbling patina that, usually, only centuries of driving rain and gale-force winds can chisel out.

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This might seem like a chest-beating, vainglorious statement of wealth, until you realise a) the Greenwich is not releasing details of expenditure (unlike the Plaza, on Central Park, which recently reopened in a £200m blaze of bling); and b) how the shafts of light play on the herringbone walls of the colonnaded courtyard. You then appreciate what a subliminally lush atmosphere results from such pernickityness.

Likewise, in a city famous for its alpha-attitude lobbies, the Greenwich instead plumps for a Southern drawl of low-key luxe – its thick oak beams are reclaimed from long-closed factories, the leaded windows feature specially commissioned glass and the terracotta tiles, hand-cut in Italy, are based on the floors of a 14th-century palazzo.

Despite all that, there’s nothing flash here, just endless layering to conjure up a truly patrician residence: warm blues and greens for the fabrics, heaven-high bookshelves lined with leather tomes and sink-in sofas filled with down feathers. The lobby segues into the Drawing Room, which has the same 12ft ceilings, but a much clubbier feel, with silvered glass rescued from the Flatiron building, huge nut-brown chesterfields and the evocative tinkle of an ever-present drinks trolley.

Not that you’ll get to linger in either on arrival. Guests are greeted kerbside and whisked straight to their room for a private, paperless check-in. The 75 bedrooms and 13 suites come with iPods and WiFi connections (the latter free, whereas many rivals charge up to $15 a day for internet access). Each room has been individually decorated and even the smallest “courtyard” category is pretty spacious by the city’s standards. (Ask for 401 or 402, which have balconies at no extra charge.)

The prize pad, though, is the two-bedroom penthouse on the eighth, and top, floor. It will have a soaring glass-ceilinged dining room, a cinema and a vast rooftop garden with hot tub and views over the city and the Hudson River. Most of the corner suites, with their art-deco curved windows, also catch the sunset over the water.

The bedrooms have cream walls, American-pine floors with antique silk rugs, handblown Italian lamps and crisply comfortable crimson, lemon and slate-blue colour schemes. The bathrooms are more exotic: vibrant Moroccan mosaic tiles have been individually laid (as many as 13,000 per bathroom), the shower doors are wrought-iron and the bespoke smellies are from the trendy organic company, McBride Beauty. And, because it’s a new-build, it has soundproofing that actually works – a big bonus in the city that never sleeps, even if it wants to.

What about food, you might ask. The hotel will have a wood-panelled outpost of De Niro’s LA restaurant, Ago, where Agostino Sciandri’s rustic Italian cucina has a cult following among Hollywood’s finest, while the more informal brasserie has beautiful hand-finished green marble pillars and a half-moon bar with a counter top made from bedrock more than 400m years old.

The final touches are still being added to its guests-only Shibui spa, which won’t open until the summer. While researching its oriental theme, the designers learnt that a rare example of an 18th-century Japanese wood and bamboo house, erected without recourse to nails or screws, was to be demolished, so they bought it, oversaw its painstaking deconstruction, then flew it and a 13-strong team of craftsmen the 6,700 miles to Manhattan to reassemble it in the Greenwich’s basement. There, a 70-year-old man, one of only five people still skilled in traditional building methods, hung upside down from its rafters, telling his son how to knot the rope ties correctly. It now forms the exposed frame of the lantern-lit pool and spa lounge.

The spa menu is also Japanese-inspired, with a shiatsu room and a range of bathing rituals, rubs and scrubs that use jasmine-based lotions and potions, freshly pounded for each treatment.

In the end, of course, a hotel is only as good as its team and De Niro has chosen his collaborators carefully. As well as his son, Raphael, his partners are the hoteliers Ira Drukier and Richard Born – as highly regarded in the hospitality world as Martin Scorsese is in his – and his general manager is Jan Rozenveld, whose CV includes Alist properties such as St Regis, off Fifth Avenue, and Tides, in Miami.

As New York has no shortage of excellent waiting staff, it’s unlikely that the lavish surroundings will be let down by lacklustre service. Although I pity anyone who works here. Imagine how often they’ll say “Good morning”, only to have the guest reply: “Are you talkin’ to me?”

Need to know

Susan d’Arcy travelled as a guest of Silverjet The Greenwich Hotel (00 1 212 941 8900, www.thegreenwichhotel.com ) has doubles from £315; until May 31, there is an opening rate of £240, room-only. Silverjet (0844 855 0111, www.flysilverjet.com ) flies from Luton to Newark; from £1,099 return. Or try Eos (0808 234 8759, www.eosairlines.com ).

Other airlines flying to New York include Continental (0845 607 6760, www.continental.com ), Virgin Atlantic (0870 380 2007, www.virgin-atlantic.com ), Delta Air Lines (0845 600 0950, www.delta.com ), American Airlines (020 7365 0777, www.americanairlines.co.uk ) and British Airways (0844 493 0787, www.ba.com ). Return fares start at about £350. For information on the city, go to www.nycvisit.com