Monte Bolca
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Monte Bolca is a lagerstätt near Verona, Italy that was one of the first fossil sites with high quality preservation known to Europeans, and is still an important source of fossils from the Eocene.
Strictly speaking, the Monte Bolca site is one specific spot near the village of Bolca in Italy, known as the Pesciara ("The Fishbowl") due to its many marine fossils. However, there are several other related outcroppings in the general vicinity that also carry fossils, such as Monte Postale and Monte Vegroni. The term Monte Bolca is used interchangeably to refer to the one, original site, or to all the sites collectively.
Monte Bolca was uplifted from the ocean floor during the formation of the Alps, in two stages: one 24 million years ago, and one between 30 and 50 million years ago. The entire formation consists of 19 metres of limestone, all of which contain fossils, but interspersed in which are the lagerstatten layers that contain the highly preserved specimens.
Within these layers, the fish and other specimens are so highly preserved that their organs are often completely preserved in fossil form, and even the skin colour can sometimes be determined. The normal rearrangement of the specimens caused by mud-dwelling organisms in the layer before it turned to stone has been avoided -- it is assumed that the mud in question was low in oxygen, preventing both decay and the action of scavengers.
The fossils at Monte Bolca have been known since at least the 16th century, and were studied intensively in the 19th century once it was definitively proven that fossils were the remnants of dead animals.
Fossils from Monte Bolca are commonly available for sale by commercial fossil dealers, and due to their popularity and preservation regularly sell for several hundred dollars.