Porticus Circumscriptus

Porticus Circumscriptus was a hall at Hogwarts Castle that could be on the Marauder's Map.^[1]^[2]

Behind the scenes

This hall can only be seen on the Marauder's Map replica on display at The Wizarding World of Harry Potter.
A "Porticus" is an entrance-porch of a church. "Circumscriptus" is likely a variation of the word "circumscript", meaning "limited", "circumscribed".

Hogwarts Castle
Locations below ground floor
Boathouse · Chamber of Secrets · Conical Crypt · Dark Hall · Deathday Party Hall · Defence Against the Dark Arts dungeon · Dungeons · Dungeon cave · Dungeon Five · Dungeon hall · Dungeon Pit · Entrance Dungeon · Forgotten Cavern · Hieroglyphic Hall · Hogwarts Basement · Hufflepuff Basement · Kitchens · Lever Rooms · Porticus Circumscriptus · Porticus Periculum · Porticus Imago · Porticus Medius · Potion-Mixing Room · Potions basement · Potions Classroom · Quidditch cave · Room of Doom · Room of Runes · Severus Snape's office · Shop · Slug Pit · Slytherin Boys' Dormitory · Slytherin Duelling Dungeon · Slytherin Dungeon · Slytherin Girls' Dormitory · Underground Chambers · Vestibule of Mischief
Paths and staircases
Boathouse passageway · Corridor of Secrets · Detention escape route · Dungeon Corridor · Dungeon Staircase · Lost Tunnel · Lower Chambers Corridor North-East · Lower Chambers Corridor West · Lower Chambers Portrait Corridor · Poltergeist Passage · Prowling Passage · Slughorn's Stairs · Undercover route to the Kitchens · Way to Courtyard
Portraits, statues and other artwork located below ground floor
Basil Fronsac · Bloody Baron · Cecilia Gallerani · Elizabeth Burke · Hooky · Mad old man · Mopsus · Old man · Percival Pratt · Salazar Slytherin · Sleeping hermit · Bearded man with book