Aschaffenburg's compact centre is dominated by Schloss Johannisburg (April-Sept Tues-Sun 9am-6pm; Oct-March Tues-Sun 10am-4pm; DM5/¬2.50, or DM8/¬4 combined ticket with Pompejanum), a very French-looking late Renaissance red sandstone pile built at the beginning of the seventeenth century for the Mainz Electors by the Strasbourg architect Georg Ridinger. It was the first purely residential princely palace ever erected in Germany, and the first to adopt symmetrical principles of a regular ground plan of four wings, though the keep of the previous medieval castle was retained as a fifth tower, counterbalancing those at the corners. The Schloss was badly damaged in World War II, and the surviving historic interiors, a suite of Neoclassical apartments on the second floor, are quite modest. A collection of eighteenth-century ecclesiastical vestments , which are displayed alongside liturgical objects and relief portraits of the archbishops, offers a more vivid evocation of the Mainz Electorate. However, these are overshadowed by the delectable collection of cork models of the monuments of ancient Rome, the earliest of which date back to the last decade of the eighteenth century and were made by the court pastry cook, Carl Joseph May. Even finer are the nine large models by his son, the civil engineer Georg Heinrich May, all of which are based on accurate on-the-spot measurements and observations.

Also within the Schloss, and covered by the same ticket, are two museums. The Bayerische Staatsgalerie on the first floor contains paintings by old German masters, including a large number by Cranach and his followers, Baldung 's Calvary and the Aschaffenburg Triptych by the Master of the Wendelin Altar . There are also Dutch and Flemish works, including examples of Rubens, Van Dyck and Dou, as well as ten small but arresting scenes from a Passion cycle by Arent de Gelder , who continued the tradition of his master Rembrandt well into the eighteenth century. Upstairs, the Städtische Sammlung contains sculptures from the time of the Schloss's construction; products of the former stoneware factory in Damm, nowadays a suburb of Aschaffenburg; memorabilia of one-time local resident Clemens Brentano, the Romantic-era writer who jointly compiled the celebrated folk-poetry anthology Des Knaben Wunderhorn ; and paintings by the Neue Sachlichkeit artist Christian Schad.

Within the palace's north wing is the Schlosskirche , though the only exterior clues as to its presence are the spire and the courtyard portal, above which is a relief of the Baptism of Christ. This is attributed to the early seventeenth-century court sculptor Hans Juncker, who made the church's pulpit and its alabaster and marble high altar , which stretches from the ceiling all the way to the vault and incorporates a dozen scenes from Jesus' life.

A few minutes' walk downstream along the Main is the Pompejanum (April-Sept Tues-Sun 9am-6pm; DM5/¬2.50), a replica of the house of Castor and Pollux in Pompeii, built by Friedrich Gärtner for King Ludwig I. Its luxuriant gardens of Mediterranean trees and plants and its vineyard sloping down to the River Main make for an enjoyable stroll. The interior, which was badly damaged in the war, was only restored a few years ago, and now exhibits original Roman antiquities alongside the mock-classical decoration.

A walk down Pfaffengstrasse from Schloss Johannisburg takes you through the heart of the Altstadt, with its narrow streets of half-timbered houses, and leads to Stiftsplatz and Aschaffenburg's principal church, the Stiftskirche St-Peter-und-Alexander . Founded in the tenth century, it combines Romanesque, Gothic and Baroque features and it's this architectural identity crisis that gives it real visual impact. The furnishings are equally diverse: they include a pognant wooden crucifix which may date as far back as the tenth century, another pulpit by Juncker, and numerous funerary monuments . Of particular importance is the magnificent bronze memorial in the north transept to one of the leading Catholic figures of the Reformation era, Cardinal Albrecht von Brandenburg; this and the accompanying relief of the Virgin and Child were both cast in the famous Vischer workshop in Nürnberg. In the last chapel of the southern aisle is a small panel of The Lamentation by Grünewald , which appears to be truncated but is in fact complete. The same artist also painted The Virgin of the Snows altarpiece in the elevated Maria-Schnee-Kapelle opposite, but the original is now in Stuppach and has been replaced here with a copy by Christian Schad.

On the north side of the Stiftskirche are late Romanesque cloisters, and the buildings around them are home to the Stiftsmuseum (10am-1pm & 2-5pm, closed Tues; DM5/¬2.50), which has wide-ranging collections, principally of archeology and sacred art. Especially intriguing are treasury items formerly belonging to Cardinal Albrecht, including a reliquary calendar in the shape of a book and Germany's oldest surviving chessboard; the latter dates from around 1300 and is a beautiful object made from wood, enamel, jasper, rock crystal, silver and clay. Among the sculptures are a panel of The Nativity by Riemenschneider and Juncker's imaginary portrait of Duke Otto of Swabia and Bavaria, the son of the founder of the Stiftskirche. Two remarkable mid-eighteenth-century painted panels mapping out the holdings of Kloster Himmelthal are the highlights of a room devoted to artefacts from Cistercian convents in the former Mainz Electorate. One of the museum's proudest possessions is the Aschaffenburger Tafel , a badly damaged but enormously powerful thirteenth-century painting of Christ as Judge which was once part of the Stiftskirche's high altar, but was later demoted to serve as a floorboard and only rediscovered during restoration work in 1986.

Just beyond the eastern end of the Altstadt is Park Schöntal , which features a lake with a ruined monastery. About 1km further east is the Fasanerie (Pheasantery): to get there, walk up Lindenallee, cross the rail bridge and continue along Bismarckallee, whose restaurants and beer gardens are popular destinations in summer. Park Schönbusch , on the western bank of the Main (reached by bus #4 from the Hauptbahnhof) is an eighteenth-century English-style landscape park, featuring a labyrinth of paths leading through woods and gardens past miniature temples and mazes. Here also is the pretty Schlösschen Schönbusch (guided tours April-Sept Tues-Sun 9am-6pm; DM5/¬2.50), the Neoclassical summer palace of the Mainz Electors.

Finally, on the southern edge of town at Obernnauer Str. 125 (reached by bus #61 or #62 from the Hauptbahnhof), the Rosso Bianco Collection (April-Oct Tues-Sun 10am-6pm; Nov-March Sun 10am-6pm; DM10/¬5) has the biggest array of racing cars in the world - some two hundred gleaming Porsches, Ferraris, Alfa Romeos and the like.