For several historians the town's name derives from the Latin name "Gelasius". Municipality in the province of Verona, located in a green valley that has the same name of the town and the nearby river, near the Lessini Mountains, the inhabitants of Illasi dedicate their activities predominantly to agriculture: famous and popular, in fact, are the wines produced here , such as Valpolicella DOC, Amarone and Recioto.
The area was inhabited since prehistoric times, as evidenced by traces found and was probably chosen for its unique geographical location, protected by mountains, rich in water and vegetation. The Roman settlers chose this area because of its proximity to the Via Postumia and subdivided the lands into centuries and assigned them to the veterans, that devoted to agriculture, started a prosperous cultivation of flax. With the dissolution of Roman Empire, presenting the ideal conditions of settlement for the new populations, Illasi became of great importance, also during the Lombard domination. The fief belonged to the La Scala until 1387, then it was disputed between the Carrara Family, the Visconti and the Serenissima Repubblic of Venice and became submitted the domain of the latter from the beginning of the XV century. At this stage, except for the period of the clashes of the League of Cambrai, the area experienced a period of quiet and prosperity. It belonged first to the Montagues and then to Pompei Families.
- the Oratory of San Rocco, whose first construction dates back to medieval times. Few traces remain of the original structure. The current building is presented with a simple façade characterized by a pediment within which is a blind lunette, has undergone several changes over the centuries that have irrevocably altered the appearance once harmonious and balanced. A single nave plan features a remarkable fresco of St. Christopher;
- the Church of Santa Giustina, built in the XVIII century and flanked by an adjacent Bell Tower of the X century;
- the XIV century Church of St. Columbanus;
- the XIX century Parish Church of Cellore;
- the XII century Abbey of San Zeno;
- the XVII century St. Anne's Church;
- the Church of San Marco;
- the medieval Castle, situated on a hill in a dominant position and believed to have been built by the Pompei Family and probably destroyed by Ezzelino Romano in the late XIII century, and later rebuilt by the Della Scala, but historical data is not unanimous. Even its military function is not sure. It shared the historical events of the area, even the most troubled incidents, it was abandoned in the XVII century and left to negligence;
- the necropolis of Arano, dating from the Bronze Age, is an important example of ancient burial customs and rites;
- the Lombard Necropolis, which reveals the cult of the dead, use of the populations originating from Northern Europe;
- the XVIII century Villa Perez Pompei with its park;
- the XVIII century Villa Pompei-Carlotti;
- the XV century Villa Settembrini;
- Villa Trabucchi;
- Villa Avresi.