The Law Library's Roman Law Collection is shelved according to Library of Congress classification. A typical call number would be KJA or JC. Search by title (e.g. A propos du contrat estimatoire par E. Thaller) or subject (Roman Law) in the MLaw Catalog. Pre-1850 texts are in the Rare Book Room.
The Roman Law Collection covers the following topics/texts:
Periodicals
Collected Works/Essay [works by a single author/commentator]
Dictionaries/Lexicons
Selected Texts/Documents in Roman Law [texts drawn from more than one work]
Pre-Justinian Roman Law
Justinian's Corpus Juris Civilis [collection of Justinian's Institutes, Digest, Codex, and Novels]
Justinian's Institutes [school text for Roman law students]
Justinian's Digest/Pandects [Roman case law]
Justinian's Codex [codified Roman statutes]
Justinian's Novels [collection of Roman constitutions]
Post-Justinian Roman Law
Treatises and Commentaries [on Roman Legal History, Roman Legal System, and Selected Topics]