The party was composed of fourteen Friends of the Yale Center for British Art touring Venice and the Veneto. They were a cultivated lot. If Yale had not educated you, then Princeton, Michigan or Vassar had. The theme of the tour was Power and Piety – not exactly Venice for beginners. We would spend a morning looking at the reception of the Renaissance in Venice, wending our way via the Miracoli, the Cima da Conegliano in San Giovanni, Bragora, and the Carpaccios in the Scuola di San Giorgio degli Schiavoni to the later Bellini altarpiece in San Zaccaria, the majestic Madonna and Four Saints.

A strange rhythm began of sun-filled mornings on the lagoon and Palladian churches in the afternoon, then back to the Gritti for compulsive viewing of CNN or BBC World News. At first, some of the party felt the irrelevance, even a shameful frivolousness, in touring Venice at a time of national calamity. Wanting to be in America as an act of solidarity played a part, plus anxiety about how to get back home at all in those terrible days following the assault. Then came the realisation that nothing could be done except to go on with the tour.

On the Friday after the attack, we were scheduled to go to Mantua. Although it is less than two hours from Venice, none of the party had been there before. At noon that day, the European Community had declared the entire continent would observe a three-minute silence to honour the dead in New York and Washington.

The ghosts of the Gonzagas are the sole heirs of the vast Palazzo Ducale, which looms over the northern edge of Mantua. Almost nothing remains of their grand collection of pictures (sold in 1628 to Charles I) except Andrea Mantegna’s small, frescoed room showing Lodovico Gonzaga and his wife Barbara surrounded by their family and court. The guidebook quotes Aldous Huxley’s dislike of the place: ‘none seemed so dead, so utterly bereft of glory’.

But, at the far edge of town, amid the soccer fields, sits the Palazzo Te, Giulio Romano’s masterpiece. Built between 1527 and 1534 as a pleasure palace and summer retreat for Federigo Gonzaga, it has the unsettling power of late-Renaissance paganism. The austere exterior gives little hint of the fantastical decorations within. Passing through the large and airy Sala di Cavalli, with its life-size portraits of horses much prized by the Gonzagas, the visitor comes to the Sala di Psiche, with its erotic banquet frescoed across two walls. The appetites of gods and men are luxuriously indulged.

The climax of the decoration comes in the Sala di Giganti. The room is shaped like a cave or grotto. There are no corners, only a vertiginous, continuously curving wall. The floor was originally cobbled and dipped away in the centre like a pond so that the viewer would be uncertain of their footing. All around the stumbling visitor raged the destruction of the Giants by the Olympian gods. Heads and limbs of the defeated Giants eight and ten feet in length crash around our ears. As Frederick Hartt once observed, it is ‘as if we were standing in a building struck by a bomb’. This morning, the gargantuan playfulness departed from Giulio Romano’s fantastical conceits; the allegory of destruction took hold.

Palazzo Te now uses one of the long ranges facing the outer courtyard for exhibitions. By good fortune, we found ourselves scrambling around a huge survey of responses to the Italian landscape with the tuneful title Un Paese Incantato. Italy as place, the beauty of its landscape, both the wild and the tended, the small corners of nature and cities, high and well-lit rooms giving on to extensive, eloquent views: these were the themes and images of the show. And it was so European. The Brits one knew – Jones, Cozens, Turner – and some of the French – Corot, obviously, and Granet – but the Germans, the Scandinavians, the Russians … they just kept coming, discovering an Italy without the impositions and pomposities of the Grand Tour; an Italy of sunlight and release, far from the cares of the barbarous north.

By now it is eleven-thirty and our punctilious Italian manager, Giuliana, is sheep-dogging us back into the bus, overly concerned about our appointment at the Palazzo Ducale. I am determined that this party of Americans will not have to observe the three-minute silence on a bus. My goal is Leon Battista Alberti’s monumental church, San Andrea.

We have to drive right around Mantua and park on the far side of the Palazzo Ducale. We are a quarter of a mile from San Andrea. Before us lies the large, irregular, and cobbled Piazza di Ducale. Through the loggias and crowded streets of fifteenth-century Mantua where cafés spill across piazzas, we round a corner and confront Alberti’s massive arched façade of San Andrea. The main west door is open. In the dusky interior, candles flicker and beckon. Even on overcast days, the transition from the outside world to the vast basilica calls for a period of adjustment. A grave, grey light fills the space, filtering into the nave from the washes of the crossing under the cupola.

Lodovico Gonzaga commissioned Alberti to design the church in 1470 to house the precious relic of the Holy Blood taken from the spear of Longinus. The relic is placed in a crypt at the crossing, surrounded by a simple balustrade. Naturally, we move down the nave to this focal point. It is a few minutes before noon. Normally, San Andrea closes at twelve, but I assure our party that today they won’t throw us out. Wrong.

At a minute to twelve, the short, balding, and bespectacled sexton begins banging shut the great west door. He speeds down the nave to the crossing and begins ordering people out of the church. Giuliana intervenes and after some dispute, the sexton, anxious not to be late for lunch, allows us to stay if we move down the nave closer to the door.

It is noon. Not a bell sounds. Our group stands silently in a loose but dignified formation. Other visitors go on reading their guidebooks. A shaft of sunlight cuts across our feet from high up on the south side. Suddenly, a group of formally dressed Italian men walk over and stand with our group. There must be about thirty of us.  Silence falls at last. No bell sounds at the end of the three minutes, but the Italians approach us. Silently, they shake our hands and nod sympathetically. We are all overcome by the quiet dignity of this show of solidarity. Tears come appropriately to many.

Outside, Mantua bustles away, preparing for lunch. We make our way through the crowds back to the Palazzo Ducale. One of our party, slightly lame, had decided to stay in a café in the main piazza. We ask him what happened. ‘Nothing …everybody went on with their business.’

Thankfully, our guide to the Palazzo Ducale is no Gonzaga groupie. We pause in the Pisanello rooms but zip through the rest until we come to the Mantegna room. Although groups are only allowed ten to twelve minutes in the small space, Mantegna transfixes us. Lodovico, letter in hand, turns to speak to his councillor who bends his head to catch his master’s word. The courtiers coming up the stairs look bored and self-important, awaiting instructions. Lodovico’s wife, Barbara, looks every inch (and there are a lot of them) the Emperor’s niece, posing grandly for the court painter. Their son is about to become a cardinal; the family is gathered solemnly to hear the good news. Mantegna hints at the Gonzaga’s tendency to obesity and to hunchbacks but, here too, is a moment of solidarity.

We are behind schedule and late for lunch. Giuliana hustles us across the Piazza di Ducale again and down the Via Buonacolsi. Apart from cars and streetlamps, nothing has changed in this street in four hundred years. The old world and the new have spoken together, and remained silent together, this morning in Mantua.