stands head and shoulders above the rest.

It isn't luxurious.

It doesn't have a pool.

But it's the ultimate retreat.

The Capanna Margherita, the Margherita Hut in English,

sits on a mountain top surrounded

by glaciers at an altitude of 4,554 metres, almost 3

vertical miles above sea level.

Apart from a tiny emergency shelter on Russia's Mount

Elbrus, it is Europe's highest building,

and no other hotel comes close.

It's the end of a sweltering week in Europe,

but we're going up somewhere where it's always snowy.

We're going up to Europe's highest hotel.

The Margherita Hut sleeps 70 and is open to all,

but getting there isn't exactly straightforward.

You start in one of two Italian villages - Alagna or Gressoney

- and ride their cable cars as high as they will go,

to 3,275 metres.

From there, it's an hour's walk to a climber's refuge

where you spend the night, and at dawn the next day

you don crampons and a rope for a five-hour glacier hike

to the hotel.

You've made it up to the Capanna Gnifetti,

a pit stop for the night before we go up early tomorrow

morning, up to the Margherita Hut.

They were both built in the middle of the 19th century

when Alpinism was just starting to take off

across this area as an upper class pursuit.

We're going on a glacier all the way

so we've got a problem of dealing with crevasses.

It will be demanding mainly because of the altitude.

So it's 5:45 and we're just about to set off up

towards the Margherita Hut.

We've got about 900 metres of vertical ascent to go,

so I better get on with it.

No one would build a hotel so high today.

The Margherita Hut is a relic of an earlier golden age

of mountaineering.

In the late 19th century little Italian villages

at the foot of Monte Rosa were booming as climbing

became an increasingly popular pastime.

Even the king and queen, Umberto and Margherita,

were regular guests.

The Italian Alpine Club ordered the construction of the hut

in 1889.

It was opened by Queen Margherita and named in her

honour, as later was a certain type of pizza.

The world wars saw an end to all that.

Tourism collapsed and the villages retreated to obscurity

- but up on the frozen summit, the hotel endured.

So we've been going for a couple of hours.

We're just at the Col du Lys which

is where we cross over into Switzerland

to cross the final glacier up to the Margherita Hut.

The big unseen danger is the altitude.

Up here there is 40 per cent less oxygen

than at sea level, which makes altitude sickness

a real possibility.

Guests at the hotel sometimes have

to be rescued by helicopter and taken back down the valley.

Most mountain huts in the Alps are halfway up the mountain,

to be pit stops for climbers on their way up to the summit.

Crazy thing about this place is they

built the refuge right on the summit itself.

Thanks, mate.

We made it.

Fantastic.

So it's 10:45.

We made it up to the Margherita Hut.

It's a long way to come for lunch

but just look at that view.

We're at 4,554 metres.

There's only two peaks in all of the Alps

and the Pyrenees that are higher than us

and yet this isn't some gnarly climber's bivouac.

There's a full restaurant, a bar.

They've even got wifi.

Claudio Bonetta is one of the team of five

who run the hotel, typically working for a fortnight

before descending for a break at lower altitude.

I asked him what it was like to work up among the clouds.

Maybe the first days when you are just arriving,

you can feel the altitude, a little bit sick.

But - then no problem - and work at the same time.

When you finish your season here, where do you go?

I'm going to holidays.

On the beach?

Yeah, on the beach.

With my girlfriend, yes, yes.

The most popular dish here is Pizza Margherita, what else?

There's also a small bar with a real espresso

machine, a tiny library, and a big sun terrace.

But the hut has always also been used

as a base for high-altitude scientific research.

I've been to thousands of hotels but this

has to be the most spectacular.

Now, though, it's time to start the long walk down.