The Temple of Debod is an Egyptian 4th century BC temple that now stands in the Parque de la Montaña near Plaza de España. While it seems out of place in Madrid, the temple has been there since 1971 when it was dismantled, shipped, and carefully reconstructed in the city. This was done to protect it from flooding caused by the Aswan Dam. Spain was chosen to receive the temple as a thank you for helping to save Abu Simbel, another archaeological site that was threatened by flooding in Egypt.
As for the temple itself, it stands behind two stone gates rising out of a calm shallow pool. Inside the temple, there are hieroglyphs as well as photos documenting its history, including the reconstruction in Madrid. The temple and gates are illuminated at night, creating a clear beautiful reflection of it in the water.
The Parque de Montaña, where the Temple of Debod now stands, also offers a comfortable retreat with grassy lawns and shade-giving trees. The view from the edge of the hillside is an amazing panorama of the city skyline and is the perfect spot to watch the sunset. Get there from the Plaza de España or Ventura Rodriguez metro stops.