Once, the western world was full of relics. The bones and skin, fingernails and even heads of saints were preserved, bought and sold, stolen and chreished. Relics of holy people and of Jesus Christ were at the heart of medieval Christianity. Today many relics have been discredited. Museums display empty reliquaries, crafted from gold and silver and laden with jewels – but bereft of the body parts that once gave them meaning.

Still, some relics are still cherished. They have survived sceptics, scientists and in some cases detailed exposure, to be revered as holy objects of awe. As the Vatican puts the bones of St Peter on display, here are the top 10 extant Christian relics, from holy shroud to sacred head.

Holy Shroud of Turin

The Shroud of Turin from a 1979 file photo. Photograph: Barrie M Schwortz/AP

Despite being analysed by scientists and discredited as a medieval forgery, this centuries-old cloth bearing the image of a man is still seen by many as the burial shroud of Christ. Its modern fame began when a photographer noticed it looks more detailed in negative, implying the image itself is a reversed "negative" imprint of a body, which some see as a bit beyond the capacities of medieval forgers.

Head of St Catherine of Siena

Detail from a painting of Saint Catherine of Siena by Fra Bartolomeo. Photograph: Arte & Immagini srl/Corbis

This has to be the grisliest relic displayed by the Catholic church – a mummified head preserved in the Basilica Cateriniana San Domenico, Siena, and still shown to visitors. Siena is a beautifully preserved medieval city, famous for its annual horse race as well as the art of Duccio, but the head of St Catherine shockingly transports you to what feels like a dark and primitive living past.

Blood of Saint Januarius

Worshippers in Naples gather every September to see a miracle at the southern Italian city's cathedral. The dried blood of St Januarius, martyred in the 4th century AD, is preserved there and has an organic connection with the city's wellbeing. Every September – and on two other days in the year – the red powder liquefies. It becomes living blood – and the city is safe from volcano, earthquake and plague.

The Holy Foreskin

St Anthony of Padua, a patron saint of lost things. By Benozzo Gazzoli.

It is said when the young Jesus Christ was circumcised, his foreskin was preserved. In the middle ages it became a much coveted relic and several churches claimed to own part or all of it. The foreskin was held to have great powers. However, the various relics of it were discredited by the end of the 18th century.

The Tongue of St Anthony of Padua

British Catholics recently gathered at Westminster Cathedral to pay respects to a piece of dried flesh and some facial skin that are said to have belonged to St Anthony of Padua. Seven hundred and fifty years ago the tongue of St Anthony was found to be perfectly preserved – an incorruptible relic. St Anthony was a great preacher, his tongue apparently holy.

The Finger of St Thomas

"Doubting" Thomas was unable to accept the resurrection even though Christ stood there before him. So Christ allowed him to put a suspicious finger inside the wound made in his side by a Roman soldier's lance. It is a moment miraculously painted by Caravaggio. If you doubt the story, you can see Thomas's finger itself, preserved in the church of Santa Croce in Gerusalemme in Rome (they've got three pieces of the True Cross, too).

Relics of Sainte-Chapelle

Stained glass windows at Sainte Chapelle church in Paris. Photograph: Pascal DelocheNG/Godong/Corbis

The French king Louis IX – better known as Saint Louis – was so proud of the relics of Christ he bought from Byzantium that he built a spendid church in Paris to house them. Sainte-Chapelle is the world's largest reliquary and one of the most ravishing of all gothic churches. Today the relics, including Christ's Crown of Thorns, are kept in the cathederal of Notre Dame.

Body of St Mark

St Mark was martyred at Alexandria and his body – natch – was miraculously preserved. It was then taken to Venice in one of the greatest relic heists of the middle ages. A gang of daring Venetians stole St Mark's mummified remains and took them to their own city, which identified deeply with St Mark. The mummy is still kept in a tomb in St Mark's Basilica, whose glories celebrate this stolen relic. The theft itself is portrayed in a masterpiece by Tintoretto.

St Cecilia

The perfectly preserved body of this young saint was found in Rome four centuries ago. The discovery was commemorated by a creepily realistic marble sculpture of the corpse by Stefano Maderno. This can be seen at St Cecilia in Trastevere, Rome, which also preserves her relics.

Head of St John the Baptist

Detail from a painting of Herodias with the Head of Saint John the Baptist by Titian. Photograph: George Tatge/Alinari Archives/Corbis

Salome famously asked Herod for the head of John the Baptist on a platter. This most famous of severed heads had a long afterlife as a relic. Amiens Cathedral was built in the middle ages as a shrine for it. A replica of the baptist's head is still kept there, although the original was stolen in the 19th century.