Gruta das Torres (Portuguese: Grotto of Towers), is a lava cave, a geological formation of volcanic origin formed from the flow and cooling of subterranean magma rivers.

The cave system formed from a series of pāhoehoe lava flows which originating from the Cabeço Bravo parasitic cone about 500 to 1500 years ago.

[1] Access to the cave was managed by the Mountaineering Association (“Os Montanheiros” – Núcleo da Ilha do Pico).

[2][3][4][5][6] The cave's uniqueness lies in its impressive drainage pattern, which can be shown by the presence of more than seven layers on the walls, with lateral benches and three cornices.

Between March 28 and April 23, 1991, a "three dimensional braided system" was documented by a team of speleologists when the cave was recorded as the longest lava tube in Azores with the explored length of 3350 metres.

[13] The liquid lava that dripped from the roof of Gruta das Torres has formed into picturesque stalactite and stalagmite and also in several other formations and shapes.

The top of the flow cooled against the air and formed a solid crust, while beneath it the liquid lava continued to move.

Some forms of plant life like ferns, mosses and lichens are also noted at the portal, floor and walls of the cave opening.

A Working Group on Volcanic Caves of Azores supported by the Azorean speleological inventory and classifying system database has identified 30 volcanic caves of rank A, which are located in the Graciosa, Pico, São Jorge, São Miguel and Terceira islands for inclusion in the UNESCO List.

Of these 30 volcanoes identified for UNESCO recognition, Pico island has the maximum number of 17 volcanic caves in the proposal, which includes Gruta das Torres.

A visitor centre built in basalt rocks and aesthetically merging with the environment, provides a guided access into the cave.

The visitors' support center at the entrance to the cave has innovative architectural features – “a circular sweep and a linear spatial organization – a sequence of programmatic spaces that prepare visitors for the spectacle below.”[6] It was awarded the "European Union Prize for Contemporary Architecture Mies van der Rohe Award 2007", in Barcelona.

[11] To achieve this, the layout has incorporated techniques of local building architecture in the form of 'currais de figueira' meaning 'fig tree walls” structure.