Marcello Venusti 
Martirio di S. Giovanni Evangelista

16th century
Fresco
Church of Santo Spirito in Sassia, Rome

The label at the church names this the "martyrdom" of St. John the Evangelist, but in the legend the boiling in oil did not succeed in killing the saint.

More of St. John the Evangelist

Photographed at the site by Richard Stracke