When in Rome (novel)

When in Rome
First edition
AuthorNgaio Marsh
LanguageEnglish
SeriesRoderick Alleyn
GenreDetective fiction
PublisherCollins Crime Club
Publication date
1970
Media typePrint
ISBN0-00-231889-X
Preceded byClutch of Constables 
Followed byTied Up in Tinsel 

When in Rome is a detective novel by Ngaio Marsh; it is the twenty-sixth novel to feature Roderick Alleyn, and was first published in 1970.

The novel takes place in Rome, and concerns a number of murders among a group of tourists visiting the city; much of the action takes place in the "Basilica di San Tommaso".