Sila Thoranam is an important landmark in heritage and archaeology and the name literally translates into garland or festoon of rocks. It is a natural stone arch, about 3 m high and 8 m wide, that was found by archaeologists while excavating a geological fault. The rock dates back to the Precambrian era and is estimated to be about 2,500 million years old, while the arch is estimated to be about 1,500 million years old. Local legends consider this to be the place from where Lord Venkateswara entered Tirumala while other legends say that the rocks made up the Lord's conch. The rock is the only formation of its kind in the whole of Asia. Apart from this, there are only two more similar formations in the entire world; Rainbow Arch Bridge of Utah in the USA and the arch that cuts through the Dalradian Quartzite in the UK.