Jeb and Blake go in search of John the Baptist's resting place.
Content Warning: Human remains on screen. Discussion of murder.
Beheading John the Baptist (wiki)
Salome (play)
In 2018 the murder of Bishop Epiphanius took place and rocked the religious community -- not important for this episode but it popped up a lot in my searching.
San Silvestro "head" shown in intro
Same - but wiki article
Nimoy Fashion Alert
(NFA Wardrobe consulting by The Hogtown Rake, Pedro Mendes)
The "head" of John the Baptist at San Silvestro:
Art historian Michael Patroconni (Petroccione?)
I think Jeb and I found this to be the most fun part of the episode:
Gerald Larue obituary
Herod Antipas (the Herod that executed JTB)
Wadi El Natrun
The Cave of John the Baptist