A sprawling underground marijuana farm was discovered on Monday in an abandoned line of Rome’s subway. The record bust in the heart of Italy’s capital was apparently produced by sophisticated cultivation systems.

Some 340 kilograms of marijuana, with an estimated market value of over 3 million Euros, have been seized by Rome’s Financial Guard. The officers also discovered a trove of high-end agricultural equipment, including the irrigation systems and artificial lighting necessary for the farm.

According to the local media reports, the officers noticed a strong smell of marijuana during a routine inspection of an underground mushroom farm.