Medieval churchmen were drawn to Rome by its power in their own present time, the sovereignty of the pontiff, the sanctity of rich churches and remarkable shrines and perhaps above all, the unrivalled juridical force of its courts and their judgments. But their entry into the arena of western Christendom's current affairs was at once and forever diverted by an encounter with the city's ancient past. Hildebert of Lavardin (c.1055-1133), Bishop of Le Mans, who, like so many others before and after him arrived to advance an appeal, captured the collision in time in a celebrated verse elegy: 'Equal to you, Rome, there is nothing though you are ruined / Broken, you speak of a greatness which once was whole' (Par tibi, Roma, nihil cum sis prope tota ruina / quam magni fueris integra, fracta doces). More often than not their time in the city did not settle their contemporary concerns. Hildebert's own supplication was unsuccessful; many others left both empty-handed and in fear of their lives, if not from the wolves hunting in the streets at night then from those figurative beasts haunting the backstairs of the Curia. Still, like Goethe's 'thoughtful man making good use of a journey' (Römische Elegien, I. 10) they looked at length on the Roman remains. Other than their own safe return, their lasting souvenir was an idea of the eternal city leavened by direct experience of its landscape and material culture. These inspired personal reflections - from memorial verses such as Hildebert's to travelogue and even gestures of autobiography - which informed readings in Rome's early history and topography for an ultramontane audience which itself might never see it.

Julian Gardner's book brings together tales told by four such travellers in the first half of the thirteenth century, between the pontificates of Innocent III (1198-1216) and Gregory IX (1227-41). Then, the papacy was at the peak of its high-medieval authority, issuing a battery of decrees and conciliar canons which aimed at nothing less than the transformation of the clergy, regular and secular, and the religious practice of their lay subjects. The gravitational pull of Rome was irresistible for those ambitious to achieve office, unavoidable for those already there. Gardner's subjects were, or were associated with one or the other: archdeacon of Brecon, Gerald of Wales (1146-1223), made four visits to the city (one of them extending to four years) in pursuit of his promotion as Bishop of St David's; the business of a Benedictine, Thomas of Marlborough (d. 1236), whose only visit (1204-6) coincided with Gerald's last, also concerned a bishopric (Worcester) but as it cut across the interest of his monastery at Evesham. The lawyer Gervase of Tilbury (c. 1150-1220) was in Rome as witness to the principal enactment of the Gregorian doctrine of the two swords: the coronation of Emperor Otho IV, whom he served as marshal, in October 1209. Fourth in the group, the shadowy Master Gregory was positioned highest in the ecclesiological hierarchy as a member of the clerical familia of Cardinal Ottone da Tonengo, Gregory IX's legate appointed to the church in England, and quite probably his chancellor.

Yet they belong together in Gardner's case-study not for their clerical career paths but for their common culture of learning. Gerald, Gervase and Thomas are known to have passed through schools now taking the shape of universities - Bologna, Oxford, Paris - and Gregory would surely not have held his office without following the same cursus honorum. They were not only well-taught but also able, active - indeed, prolific - writers. What they met in Rome they passed on in personal accounts which, Gardner argues, moulded the profile of the classical capital in the eyes of later medieval readers.

The historical and literary works whose knowledge prepared them for the sights of the city were surely as similar as their scholastic education but when they walked the streets for themselves their responses were each their own. The monk Thomas could not quite shrug off the weight of his mission to the Curia. His description of the 'perils and thrills [of] the cockpit' (34) was vivid but his line-of-sight scarcely reached beyond the pontiff's lavish palace of the Lateran. From his, undoubtedly nervous point-of-view, the city's most monumental presences were all gathered there.

Perhaps because of the more privileged circumstances of their visit, Gervase and Gregory gave close attention to all they saw. Gervase described the greatest of the buildings inside and out with an attorney's attention to detail. His account captures his passage through the city, counting the steps he climbed in the Column of Trajan. It was the Rome of Mother Church which he best recalled not only the grandeur of the papal palaces and principal churches - St John, Lateran and St Peter's - and monasteries but also the energy of their religious life, such as the icon of Christ in the sancta sanctorum reliquary or the patron saint at the abbey of Sant'Andrea. He also noticed the Egyptian style of some of the newest decorations such as obelisks, pyramids and even sphinxes in the south walk of the Lateran cloister, an expression of the focus of crusade ambition following the fall of Jerusalem (1187). At times the self-absorbed Gerald appears as the prototype of the modern tourist approaching the city as the backdrop to his own personal timeline. But he cast his eye over the churches as a practising priest, distinguishing between principal and subordinate altars in the Lateran and describing a procession at St Peter's as a ship in full sail.

Alone of the four, Master Gregory gave most attention to the monuments of antiquity. His enthusiastic inventorising of surviving statuary has caused scholars to doubt its authenticity as a first-hand account but Gardner maintains that such thoughtful recording of remarkable remains such as the bronzes at the Campus Lateranensis 'rings true' (47).

Gardner is an historian of Italy's architecture and art and he weaves together these witnesses above all to document the creative development of the city under the reforming popes, the embrace of ancient motifs and the enrichment by the contemporary art and craft of the Cosmati workshop, generously illustrated with thirty-five colour plates. Consequently, he does not pursue textual history very far. Gardner's concluding account of 'aftermaths' concerns the tourists not the reception of their texts. Even so, his detailed, digressive readings are engaging and rich with insights into the material, political and social culture of the centre point of Western Church.

James Clark