15 March – Saint Longinus

Rabbula Gospels (Notice the label on the figure to the left of Christ holding the spear in the 6th-century Rabbula Gospels.  The Greek letters spell LOGINOS [ΛΟΓΙΝΟϹ]).
Chapel of Theodotus in Santa Maria Antiqua (with depiction Pope Zacharias, whose feast day is also today)
Annus Dierum Sanctorum
Accedet homo ad cor altum.
Man shall come to a deep heart:
Psalm 63.7
Unus militum Lancea latus eius aperuit.
one of the soldiers with a spear opened his side.
John 19.34
vulnerasti cor meum.
Thou hast wounded my heart.
Canticles 4.9

Modern Hagiography

Martyrologium Romanum (16 October)

Roman Martyrology

Sanctorale Catholicum

Lives of the Saints by Sabine Baring-Gould.

Our Birthday Bouquet Culled from the Shrines of the Saints and the Gardens of the Poets by Eleanor C. Donnelly.

Pictorial Half Hours with the Saints by Auguste François Lecanu.

La vie des saints

Biblical Text

John 19.34

Medieval Hagiography

BHL, Supplement

Acta Sanctorum

Gospel of Nicodemus

The Golden Legend (and illustrations)

Art & Architecture

Index of Medieval Art

Catalogo generale dei beni culturali

BeWeB

Portail Biblissima

POP : la plateforme ouverte du patrimoine

Warburg Institute Iconographic Database

Guide to Christian Iconography: Images, Symbols, and Texts

Google Arts & Culture

Chapel of Longinus in San Pietro in VaticanoStatue by Bernini

Saints and their Attributes

Sacred and Legendary Art volume II by Mrs. Jameson.

A Handbook of Christian Symbols and Stories of the Saints as Illustrated in Art by Clara Erskine Clement.

Lives and Legends of the Evangelists, Apostles, and Other Early Saints by Mrs. Arthur Bell.

The Saints in Art with Their Attributes and Symbols, Alphabetically Arranged by Margaret E. Tabor.

Saints and their Symbols: A Companion in the Churches and Picture Galleries of Europe by E. A. Greene.

The Saints in Art by Joseph Maria von Radowitz.