Case Study · Archaeological Geophysics

Mapping Two Ancient Greek Cities Without Digging: GPR at Lechaion and Sikyon

A peer-reviewed dual-site Ground Penetrating Radar survey in the northern Peloponnese revealed buried urban complexes, demolished structures and a probable ancient lagoon — all without disturbing a single square metre of protected ground.

Location: Lechaion & Sikyon, Corinthia, Greece · Fieldwork: June 2024 · Published in ArcheoSciences 49(1), 2025 · Client context: Lechaion Harbor and Settlement Project (LHSP) & University of Cyprus / University of Thessaly research teams

The Challenge

Lechaion was the western harbour of ancient Corinth — one of the most important ports of the classical Mediterranean. Sikyon, a few kilometres away, is a planned Hellenistic city laid out on a plateau of vineyards and olive groves. At both sites, excavation is slow, expensive and by definition destructive. The research teams needed to answer a question familiar to every ministry of antiquities, port authority and infrastructure planner from Athens to Abu Dhabi: what lies beneath the surface, exactly where, and at what depth — before anyone breaks ground?

Earlier magnetic surveys at both sites had suffered from noise caused by agricultural activity and modern disturbance. GPR, by contrast, had consistently produced clean, interpretable imagery of buried architecture. The 2024 campaign was designed to push that advantage further.

Our Method

Rather than relying on isolated radar profiles, we designed the survey around dense, grid-based acquisition: parallel bi-directional transects spaced 50 cm apart, covering each target area completely. Every trace was positioned with GNSS (including RTK), so that each buried target could be pinpointed in both local and geographic coordinates.

Grid coverage is what turns radar data into archaeology. It allows the construction of horizontal depth slices — plan-view maps of the subsurface at successive depth intervals — which reveal the spatial layout, orientation and extent of buried features in a way no single profile ever can.

All datasets passed through a single standardised processing pipeline: time-zero correction, gain control, bandpass and background-removal filtering, 2D migration, and velocity estimation through hyperbola fitting. The output was a stack of georeferenced depth slices at 10 cm intervals, rectified in GIS and overlaid on aerial imagery and the topographic plans of each site — ready for direct archaeological interpretation.

Hardware-Agnostic by Design

Two different GPR systems, with different antenna frequencies, were deployed side by side. This was deliberate. Lower frequencies see deeper; higher frequencies resolve smaller, shallower targets. Used together, the two datasets cross-validated every anomaly and covered the full depth range of interest — from 0.7 m down to roughly 3 m depending on soil conditions.

At Geomorph Imaging Solutions we are hardware-agnostic: we select and combine whichever instruments the geology, the target and the project budget demand. The value we deliver sits in survey design, processing and interpretation — not in a logo on an antenna.

Results

Sikyon: the buried city grid, confirmed

Southeast of the ancient Agora, the depth slices revealed multiple linear reflectors aligned precisely with the city’s known north–south / east–west street grid. The imagery indicates two to three distinct building complexes, subdivided into compartments, lying between roughly 70 and 180 cm below today’s surface. The density of structures increases towards the southeast — a direct, actionable guide for where future excavation trenches should go.

Lechaion: a hidden lagoon and demolished structures

Southwest of the site’s excavation storage area, the shallow layers were quiet — but at depth, a striking high-conductivity anomaly of approximately 15 × 50 m emerged, extending 80–150 cm below the surface. Its shape is faintly visible in 2007–2009 aerial photography from the Greek Cadastre, and it is best interpreted as part of an ancient lagoon system that once served Corinth’s great harbour — a finding with direct implications for reconstructing the classical shoreline. Around the small basilica identified in previous seasons, both radar datasets independently mapped debris fields consistent with demolished architectural structures.

Why This Matters Beyond Greece

The soil conditions we worked in — a dry coastal plain at Lechaion and a well-drained agricultural plateau at Sikyon — are directly comparable to environments across Cyprus, Israel, the Gulf states and the wider Eastern Mediterranean. The same methodology applies wherever cultural heritage and modern development meet: pre-construction archaeological screening, port and coastal-zone studies, heritage-site management plans, and the documentation of buried structures ahead of major infrastructure projects in Greece, Cyprus, Israel, the UAE, Saudi Arabia and Bahrain.

Depth slicing, GNSS-referenced grids and rigorous, publication-grade processing turn a geophysical survey from “there is something down there” into a mapped, measured, decision-ready plan of the subsurface.

Full publication: Sarris A., Arvanitis M., Scotton P., Spiropoulos G., Lolos Y. (2025). “Dual Insights: Exploring Lechaion and Sikyon with Diverse GPR Technologies.” ArcheoSciences 49(1), 151–154. Presses universitaires de Rennes.