Italian authorities made a startling discovery behind a secret tiled door in a shower wall in a home on the island of Sardinia.

Investigators found a huge, 5,400 square-foot greenhouse containing as many as 500 marijuana plants, according to CNN.

Specialized lamps were used to heat the plants and pumps and fans were operating on stolen electricity, CNN reported, citing police officials.

The homeowner was arrested and is facing charges including illegal production and possession of drugs.

WPVI-TV reported authorities seized the plants, a gun and ammunition.