Gruta Rei do Mato, Limestone cave formation in Sete Lagoas, Brazil

Gruta Rei do Mato is a limestone cave 62 km from Belo Horizonte, at the BR-040 interchange for Sete Lagoas. Its 998 m of passages, 220 m open to visitors, drop 31 m through four chambers. The Rarities Hall holds parallel calcite columns over 20 m high and 20 m in diameter.

The cave lies in the Sete Lagoas Formation, part of the Lagoa Santa Karst north of Belo Horizonte. On 25 August 2009, State Law 18.348 made it the Gruta Rei do Mato State Natural Monument, a fully protected conservation unit covering 998 m of passages, of which 220 m are open to visitors. Its four chambers hold rock paintings dated to about 6,000 years ago.

The cave's name comes from a man of unknown identity who crossed the woods daily on his way to town and was called Rei do Mato, possibly a fugitive from the 1930 Revolution. In the small cave beside it, called Grutinha, paintings were made with blood and vegetable fat, and petrified indigenous tools were found buried in good condition.

The cave lies at the edge of the BR-040 highway, by the off ramp to Sete Lagoas, 62 km from Belo Horizonte; bus, taxi or car all reach it. Of the monument's 998 m, 220 m are open to the public, with a 31 m drop between entrance and lowest point. The walkway project took over two years and was built as urbanisation, not just access and lighting.

In the Rarities Hall stand the Torres Gêmeas, twin calcite columns over 20 m high and 20 m across, found in Brazil only here. The cave also holds a resin replica of Xenorhinotherium bahiense, an extinct Pleistocene mammal whose bones were found in a small cave nearby.