Can urban planners rely on Large Language Models? An ex-ploratory evaluation of four frontier models on two contested Greek masterplans

Can urban planners rely on Large Language Models? An exploratory evaluation of four frontier models on two contested Greek masterplans Supplementary materials Aristotelis Vartholomaios 1* and Dionysia Georgia Ch. Perperidou 2* 1. Department of Planning and Regional Development, University of Thessaly, Pedion Areos, 38334 Volos, Greece; [e-mail]2. Department of Surveying and Geoinformatics Engineering, University of West Attica, Egaleo Park, Ag. Spyridonos Str., 12243 Athens, Greece, [e-mail] This repository accompanies the study "Can urban planners rely on Large Language Models? An exploratory evaluation of four frontier models on two contested Greek masterplans". The study performed a structured prompt–response experiment: four frontier LLMs (Spring 2026: ChatGPT 5.1, Claude Opus 4.6, Gemini 3.0 Pro, Grok 4) were asked to appraise two contested Greek urban regeneration projects (Hellinikon, TIF-HELEXPO) under four prompt framings, yielding a 32-run matrix (2 cases x 4 prompts x 4 models). The repository contains every artefact produced in the study: the prompts as administered, the factsheets given to the models, the verbatim model responses, the validation rubrics, human validation and analysis outputs.