Lisbon Cathedral (Sé de Lisboa)

The Sé, Lisbon's cathedral, is the oldest church in the city. Work began in 1147, the year Afonso Henriques took Lisbon from the Moors, and it was built on a site that had already been sacred for centuries. With two crenellated towers flanking a rose window, the west front looks more like a fortress than a church, a reminder of the uncertain times in which it was raised.

The building has been altered many times. Earthquakes, including the great one of 1755, damaged parts of it, and successive rebuilding added Gothic, Baroque, neoclassical and Rococo work to the Romanesque core. The result is a mixture of styles: a sober Romanesque nave, a Gothic ambulatory behind the main chapel with side chapels and tombs, and a main chapel later rebuilt in a more decorative manner. A twentieth-century restoration stripped away some later additions to bring back the medieval look of the exterior.

The most unusual part of a visit is the cloister. Excavations begun in 1990 in its central courtyard have exposed layers of the city's past: a Roman street lined with shops, part of a Roman kitchen and drainage channel, traces of Visigothic buildings, and red-painted walls from the mosque that stood here before the cathedral. Walkways let you look down into the dig, and it is one of the best places in Lisbon to understand how deep its history goes.

The nave can usually be entered without charge outside services, while the cloister and other areas require a ticket. This is a working cathedral, so dress respectfully, keep your voice down and expect parts to close during Mass and ceremonies. A visit takes about 45 minutes. The cathedral steps and the small square in front are good places to watch the yellow trams squeeze past on the steep street.

The Sé sits between the Baixa and Alfama, so it fits naturally into a walk uphill to the castle. Tram 28 and tram 12 stop right outside. From here, continue up to the Miradouro de Santa Luzia and Portas do Sol for views across Alfama's rooftops to the river, or head down to the Baixa. The Church of Santo António, built on the traditional birthplace of Saint Anthony of Lisbon, is across the street.