The plateau group of Colfiorito has an extension of about 50 kms. and the seven basins forming it are situated between 750 - 800 mts above sea-level.
The most important karst phenomenon of the Marsh of Colfiorito is the swallow hole of Molinaccio, while the marsh vegetation (Hordeo-Ranunculetum velutini, Caricetum gracilis, Phalaridetum) is disposed in concentric circles.
The marsh is an important rest area for the migratory avifauna typical of the wetlands (grey herons, purple herons, bitterns, little bitterns, mallards, shovelers).
The presence of the eagle owl and of the wild cat is relevant in the nearby Selva di Cupigliolo.
The marsh of Colfiorito and the Plains are generally one of the most interesting natural elements in the Apennine chain for their geomorphological, geological, hydrological, paleontological, botanical, historical, and agronomical features, and for their landscape.
The hydrology of the area is of particular importance for its role as a nourishing basin of the main drinking and hydromineral springs of Umbria.
The presence of the Protoumbrian and Umbrian civilization is demonstrated by important urban finds and by necropolis.
Of all the pre-Roman settlements the main one is that of Mt. Orve, surrounded by walls made of calcareous rocks and with proto-urban features. The Plestia area was the seat of of a Roman Town Hall already in 178 BC.
The expansion of the human presence in the plateaus is linked to the richness in waters, the cultivation, the altitude of the ground, and to the fact that Colfiorito was the crossroads of the most important routes crossing the Central Apennines.
In the 5th century BC, Plestia had its own bishop and the city is mentioned in the certificates of the Emperor Ottone III in 996.
Under the pressure of the Gothic, of the Longobard, and of the Hungarian invaders, the urban structure dissolved and the inhabitants returned to the hills where the old castles stood.
In the 12th century, the plateaus housed a new civil-political organization with castles (Anifo, Lignano, Popola), with monasteries (Sant'Andrea di Gricciano, Sant'Angelo di Bagnara), and hermitages.
In 1269 the Castle of Colfiorito was built, but Santa Maria di Plestia has more important historical features. The Sanctuary rises isolated at the confluence of old roads and on the Roman temple and the early Christian Basilica ruins.