A new roof terrace in the heart of Venice, at the Fondaco dei Tedeschi

The Fondaco dei Tedeschi (also known as the Fontego dei Tedeschi) is a large historic building next to the Rialto bridge in the heart of Venice. Built in the 16th century, it used to be the trading post of German merchants in the city, and its exterior was decorated with frescoes by Giorgione and Titian. Until a few years ago, this was Venice's central post office, shabby but imposing. The last time I visited, I was collecting a package of books.

Now the building has been restored and transformed into a high-end shopping experience. Somewhere between a mall and a department store, the new-look Fondaco dei Tedeschi is made up of concessions selling luxury brands - basically like an airport shopping experience but in fancier surroundings. There's still an old well head in the central courtyard, but the space has now been covered with a roof. The interior is smart and imposing, but of course the building's old, shabby sense of history has vanished for ever. Though the luxury fabrics, jewellery and leather goods on display are, I suppose, a kind of connection to the building's earliest incarnation and to Venice's mercantile past.

The main reason for visiting the Fondaco dei Tedeschi isn't the fashion, though. The restored structure is a sight worth seeing, but best of all - if you can ignore the implications for the building's historic integrity - is the new roof terrace. High above central Venice, this small platform offers a unique viewpoint over the city. I visited on a misty winter day and Venice looked marvellously atmospheric laid out below, red roof-tops stretching into the murk. On a clear day you'll have views across the lagoon and as far as the Dolomites.

Entrance to the roof terrace is free, though numbers are limited. Only 80 visitors are allowed up during each 15-minute slot; you can get a token for the next available slot at a 'concierge' desk at the top of the escalators on the fourth floor. On a busy winter's day when the city was full of Italian visitors, I had to wait about 25 minutes.

My tip is to visit on the hour, ideally at midday, when you'll hear all the church bells of Venice ringing out around you, and even see one or two of them swinging in their high belfries.

The Fondaco has another attraction to tourists in Venice. It has toilets (fourth floor) which when I visited were both free to use, and clean - a very convenient resource in a city where public toilets are scarce and expensive.

There's a smart café in the central courtyard, and expensive Italian foodstuffs for sale on the ground floor, with men's and women's fashion, perfumes, jewellery and accessories on the floors above.

As well as the festive Christmas trees, the loggia parapets were decorated with gorgeous reproduction historic fabrics by the Venetian firm Rubelli.

Excellent free-of-charge opportunities like this don't always last in Italy, and I'm unsure if permanent public access to the roof was a condition of planning permission, so do add this to your itinerary if/while you can. A visit to the roof terrace is a memorable experience and an addition to the must-sees of central Venice.

Other high viewpoints offering different perspectives over Venice: the Campanile di San Marco (admission fee), Campanile di San Giorgio Maggiore (admission fee), Skyline bar at the Hilton hotel (free entry, expensive drinks), the Scala Contarini del Bovolo (now re-opened; admission fee). And of course from various little private wooden terraces perched above rooftops, the altane of Venice, if you are lucky enough to get access to one. And less all-encompassing views can be enjoyed from the top-floor windows of tall buildings which are sometimes open for exhibitions, including the Conservatorio di Musica.

You can read a lot more about Venice including other insider tips and background information in my guidebook: Italy Heaven Guide to Venice.