Saint Michael's Cave is a series, or network of caves made of limestone, which are found on the Rock of Gibraltar. St Michaels Cave is located on what is called the Upper Rock, inside the Upper Rock Nature Reserve of Gibraltar.
The cave was created by the slow seepage of rainwater through the rock, which turned into a carbonic acid solution that actually dissolved the rocks of the cave. The process made the tiny cracks of the geological faults of Gibraltar grow into very long passages and deep caverns over the thousands of years of its formation. The Cathedral Cave, part of St Michaels cave was at one time thought to be bottomless, and was long spoken of in the legends of Gibraltar.
The Rock of Gibraltar has long been considered to be one of the pillars of Hercules, and this too adds to the mystique and legend, and since it hosted the cave, the caverns themselves were thought to be the Gates to Hades, or Hell, an entryway to the Underworld where the dead rested.
In the latter part of 1974, proof that the cave was known to and used by prehistoric men was made clear with the finding of art on the cave walls, showing an ibex drawn there that was traced to the Solutrean period (dating the cave art to about 15-20 thousand years ago), but later, two Neanderthal skulls that were found in Gibraltar tell us that this cave could have been discovered and used as early as 40,000 BC.
References:The Temple of Edfu is one of the best preserved ancient shrines in Egypt. It was built in the Ptolemaic Kingdom between 237 and 57 BC.
Edfu was one of several temples built during the Ptolemaic Kingdom, including the Dendera Temple complex, Esna, the Temple of Kom Ombo, and Philae. Its size reflects the relative prosperity of the time. The present temple initially consisted of a pillared hall, two transverse halls, and a barque sanctuary surrounded by chapels. The building was started during the reign of Ptolemy III Euergetes and completed in 57 BC under Ptolemy XII Auletes. It was built on the site of an earlier, smaller temple also dedicated to Horus, although the previous structure was oriented east–west rather than north–south as in the present site.