Jonathan Glancey admires the Villa Rotunda
Andrea Palladio (1508-80) is the renaissance genius who shaped not only Vicenza but created some of the finest country houses of all time.

These can be found along the Brenta Canal and the Po Valley between Venice and Vicenza. One of the finest is Villa Capra (better known as the Rotonda and built in 1550-1551 for Cardinal Capra) an exquisite villa famous for its four identical entrance facades - more a summer retreat than a workaday home - which is reached via an easy and delightful walk from the centre of Vicenza.

If it looks familiar to British eyes, this is because the house was reinterpreted both at Chiswick by Lord Burlington and at Mereworth in Kent in the 18th century. It also played a starring role in Joseph Losey's luscious film version of Mozart's Don Giovanni.

Palladio was the hero of what we call the Palladium movement, a British architectural fashion nurtured by Lord Burlington which ousted the theatrical Baroque of Wren, Van Brugh and Hawksmoor, replacing it with a rigorous and chaste style that stayed in fashion for around 50 years and gave Britain the country houses we know and cherish today.

Thomas Jefferson, president and author of the American Declaration of Independence, took Palladio's style with him to Virginia where he tended the flowering of a transatlantic Italian renaissance.

Palladio has cast a long and perfectly proportioned shadow across the face of the western world. Arguably he is the most influential of all architects and the charisma of his perfect buildings continues to fascinate us.

Looking at the Rotonda it is easy to see why. The house, its proportions rooted firmly in the golden mean and a related series of sophisticated mathematical ratios, is as complex and as harmonious as a Bach fugue. It is also extremely beautiful, enhances the landscape and is handsomely crafted. And it is a delightful architectural puzzle - is it a square house built around a dome, or a circular house with square walls?

Palladio was popular with clients - the new Venetian rich who wanted model farms to escape to after long seasons making large amounts of money from banking and international trade in Venice - and with workmen too. Clients loved him because he endowed them with immaculate taste and sophistication; builders respected him as a fellow craftsman who had worked his way up the hard way.

Born in Padua, Andrea di Pietro della Gondola was apprenticed as a stonemason. The name we know him by is a nickname derived from Pallas, goddess of wisdom and was bestowed on the brilliant young mason by his patron and mentor, Gian Giorgio Trissini, who introduced Palladio to the worlds of antiquity, classicism and ancient Rome. Trissini took his protege to Rome in 1545 where they stayed until 1547. Palladio brought Rome back in his satchel and reinterpreted its finest architecture for the Venetian bourgeoisie. He did not disappoint them.

Out in the country around Vicenza it is hard to know where to start a tour of Palladio's peerless farmhouses. There are a large number of them and they are all magnificent. Perhaps the best starting point is the Villa Saraceno, now owned and rented out by the Landmark Trust (01628 825925). Book well ahead and live in the style of Palladio.

Then compare it to Villa Pogliano, Villa Zeno, Villa Barberi, Villa Mocenico. Each is a brilliant marriage between ancient Rome and the (modern) world Palladio and his clients operated in.

A tour of these houses will take you through delightful countryside - not grand, but happily settled - and make you hungry for more. Travelling may tire you, but Palladio never will.