A Eurostar trip across the Channel gives SIMON EDGE a bird's-eye view of the French capital

IT'S A glorious autumn day and I'm standing on an artificial-turf rooftop in the heart of Paris.

The wedding cake finery of the Paris Opera's Palais Garnier (of Phantom fame) is looming over the pediment.

Beyond stretches a panorama from the hilltop La Basilique du Sacr©-Coeur in the north to the Tour Montparnasse skyscraper in the south.

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What is striking is that most of the rooftops are a uniform height with only a handful of iconic landmarks bursting through.

This is the Galeries Lafayette, one of the city's four glittering department stores as I've never seen it before.

The store's massive five-storey cupola is a visitor attraction in its own right but the roof is a gem Parisians prefer to keep to themselves.

The shop's owners once offered a small fortune to anyone who could land a plane on it.

A madcap aviator called Jules V©drines won the prize in 1919. More recently tennis courts were installed up here for the French Open but if you want you can just bring a sandwich and have a picnic.

I have come to explore some of the quirky things Eurostar is offering at no extra charge to its rail ticket holders.

At Galeries Lafayette you get a 10 per cent shopping discount on presentation of your train ticket but I've joined a tour of the store that celebrates its architectural finery.

You can book by emailing the shop in advance but the roof is open to all.

We're also going to the Mus©e du Quai Branly, former president Jacques Chirac's pet project displaying objects from France's colonies.

Your Eurostar ticket gets you two-for-one entry into the temporary exhibition, currently a rather stodgy show about the Maoris, as well as into the permanent collection.

The best bit for me is the building itself, an iron snake on stilts above a pampas grass garden.

From the terrace of the museum's restaurant with the Seine slipping past below it feels like the neighbouring Eiffel Tower is sprouting out of your afternoon tea.

Then it's off to the Tuileries formal gardens, between the Louvre and the Champs-Elys©es, where Parisians come to stroll or sit quietly in the autumn sun.

We are visiting the Jeu de Paume, the beautifully restored gallery dedicated to photography.

The show features the work of Sixties snapper Diane Arbus with around 200 of her eccentric portraits.

Again show your Eurostar ticket and you get two-for-one admission.

The same deal is on offer at the Mus©e d'Orsay, the converted railway station on the left bank of the Seine which is home to a collection of Impressionist paintings; the Grand Palais, the city's main venue for blockbuster art shows; the Cit© de la Musique in the 19th arrondissement where you could also treat yourself to a concert; and the Mus©e d'Art Moderne in a pavilion built for the 1938 Paris exposition.

There's a danger of getting cultured out and part of the point of Paris is lingering in caf©s where you can spend all morning over one thimble of espresso.

For a relaxing lunch your Eurostar ticket also comes in handy.

It gets you a 50 per cent discount on food at 10 different restaurants (you can find all the details of food and museums by Googling Eurostar Plus).

If you are on a budget I recommend Aux Bons Crus in the Rue des Petits-Champs, which is one of those identikit Paris streets that run along the back of the Palais-Royal.

They do a fragrant crottin de ch¨vre en cocotte, creamy melted goats' cheese that's served as a piping hot soup for ?8.50 and a mean rump steak in wine sauce for £17.

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With the discount you've got an amazing two-course meal for a little over £10.

Back on the Galeries Lafayette roof with my serene view of the city, I had no idea quite how much of it I would end up covering.

Armed with a Metro ticket that gives you unlimited travel over a three-day period it's easy to get around.

When you're doing most of it at half price, somehow that makes it all the better.

THE KNOWLEDGE

Eurostar (08432 186 186/ www.eurostar.com) offers return rail travel from London St Pancras International to Paris from £69.

Hotel du Triangle d'Or (dialling from the UK: 0033 1 4742 2505/ www.hoteldutriangledor.com) offers doubles from £162 per night (two sharing), B&B. French Government Tourist Office: 0906 824 4123/ www.franceguide.com