The Gothic Quarter, Honestly

Start at the head of Carrer del Bisbe, where two thickset towers flank the square and the reconstructed aqueduct arches run above. This was the north-west gate of Barcino. The towers are Roman at the base and rebuilt higher up - a useful lesson in how to read this quarter.

The most photographed thing in the Gothic Quarter is not medieval. The Bishop's Bridge was built in 1928 by Joan Rubio i Bellver, a collaborator of Gaudi's, to link the Palau de la Generalitat to the canons' houses opposite. Rubio wanted to remodel the whole street in flamboyant neo-Gothic; the city said no, and the bridge is all that was built.

Look up at the underside for the carved skull with a dagger through it, and the legend that the city will fall if you stare at it. The legend is as modern as the bridge.

The civic heart: the Generalitat, seat of the Catalan government, faces the Ajuntament, the city hall. A Roman forum stood on this spot.

Duck into the courtyard at Carrer del Paradis 10 - the doorway is easy to walk straight past. Inside stand four Corinthian columns of a first-century BC temple to Augustus, on Mont Taber, the high point of the Roman town. Free. Open Monday 10:00-14:00, Tuesday to Saturday 10:00-19:00, Sunday 10:00-20:00.

A near-perfect medieval square. Beneath it, the MUHBA city history museum opens about four thousand square metres of excavated Roman Barcino - streets, a laundry, a fish-sauce factory, a winery. Around 7.50 euro; closed Mondays. Check the museum's site before you go: municipal museums here are usually free on the first Sunday of the month and on Sunday afternoons.

The best-preserved stretch of the Roman wall, with defence towers and the medieval Chapel of Santa Agata riding on top of them. Free, and open to the sky at any hour.

16 euro, which includes the rooftop terraces, reached by lift. Inside: a fourteenth-century cloister with a garden and thirteen white geese, one for each year of Saint Eulalia's life; the choir stalls of 1390; and the Chapel of the Sant Crist de Lepant. Open Monday to Friday 09:30-18:30, Saturday 09:30-17:15, Sunday 14:00-17:00, with last entry about 45 minutes before closing. Outside ticketed hours the cathedral is open for worship only.

If the price gives you pause, see Santa Maria del Mar on the Top Sights page: 8 euro including its roof terraces, and a finer interior.

A small square with a pockmarked church wall, and the most sobering stop on this walk. On 30 January 1938, during the Civil War, Italian aircraft flying for Franco bombed this square. Forty-two people were killed, about twenty of them children sheltering in the church. For decades the Franco regime claimed the marks were made by firing squads. They were not; they are shrapnel. The square is a school playground today - go early or at a weekend if you want it quiet, keep your voice down, and don't photograph the children.

Antique shops, bookbinders and the slow end of the quarter. Wander.

Not medieval - laid out between 1848 and 1859 on the site of a demolished convent - but worth the detour for one thing: the two lamp posts flanking the fountain are Gaudi's first paid public commission for the city, designed in 1879, six-armed and topped with the winged helmet of Mercury. Drink elsewhere; the terraces here are priced for people who don't know better.