Janičův Vrch Quarry was declared a nature sanctuary in 2014. It covers the entire area of the flooded limestone quarry by Mariánský Mlýn and the immediate surrounding area. Janičův Vrch (historically 332 m) towered into the sky to the north-west of Holy Hill, from which it was separated by just a narrow pass. Only a small number of rare plants survived here after the quarry had been worked out. The original rocky grasslands were preserved on a remnant of the western foothill, with the occurrence of rare and endangered species such as the sprawling needle sun-rose, Baden’s bluegrass, the mountain germander and the bellflower Campanula sibirica, shifting into a fragment of Sesleria grassland dominated by the blue moor-grass Sesleria caerulea. The rock-rose Helianthemum grandiflorum ssp. obscurum, the bloody crane’s-bill, the sulphur cinquefoil and Peucedanum cervaria, for example, still survive on the remnants of broad-leaved dry grassland on the former south-east foothill. The area of water covering the flooded quarry is also an important refuge for fish-eating birds such as the grey heron, the night heron, the kingfisher and the common tern. As well as familiar swallows and swifts, exquisitely coloured bee-eaters can also be seen at the quarry. The walls of the quarry are sometimes used for breeding by our largest owl – the eagle owl. The water in the quarry also attracts amphibians, and you can see the marsh frog and the edible frog here, and perhaps the rarer smooth newt and the fire-bellied toad. The amphibians in the quarry feed our most abundant snake – the grass snake.
The nature sanctuary is open to the public, though the number of visitors is limited to a maximum of 100 in the summer months from June to September and an admission fee is charged.