Churches and cathedrals — hidden gems

At Justo Sierra 71, behind a neo-colonial facade, a replica of a temple in Šiauliai: Mexico's only Sinagoga Histórica.

In Barracas, the 1876 neo-Gothic church for Felicitas Guerrero, with túneles from 1893 and the Templo Escondido: tours only at month's end.

In Marrakech, in the Guéliz district, the church of Saints-Martyrs holds a mosaic altar bearing the Arabic inscription "Allah Mahabba".

The Ruprechtskirche, Vienna's oldest church: Romanesque stone, stained glass from 1370 and bells from 1280, on the Danube Canal.

In Prague, in an Old Town lane, the Basilica of St James guards a mummified arm, a restless tomb and a great organ.

On the Prinsengracht a façade so sober it disappears among the houses: inside, a monumental hall and a great Smits organ.

The monastery of São Vicente de Fora in Lisbon: azulejo cloisters, the Braganza pantheon and a panoramic terrace, almost always empty.

In Malasaña, Madrid, a baroque church with an elliptical plan, its walls and dome entirely frescoed. Limited opening hours, almost always deserted.

A 12th-century Romanesque church with a Gothic cloister, tucked away in a lane just steps from Plaça Catalunya, in Barcelona.