The bluebirds are a group of medium-sized, mostly insectivorous or omnivorous birds in the genus Sialia of the thrush family (Turdidae). Bluebirds are one of the few thrush genera in the Americas. They have blue, or blue and red, plumage. Female birds are less brightly colored than males, although color patterns are similar and there is no noticeable difference in size between sexes.



Bluebirds are territorial, prefer open grassland with scattered trees and are cavity nesters (similar to many species of woodpecker). Bluebirds can typically produce between two and four broods during the spring and summer (March through August in the Northeastern United States). Males identify potential nest sites and try to attract prospective female mates to those nesting sites with special behaviors that include singing and flapping wings, and then placing some material in a nesting box or cavity. If the female accepts the male and the nesting site, she alone builds the nest and incubates the eggs.

Predators of young bluebirds in the nests can include snakes, cats and raccoons. Non-native and native bird species competing with bluebirds for nesting locations include the Common Starling, American Crow, and House Sparrow, which take over the nesting sites of bluebirds, killing young and smashing eggs and probably killing adult bluebirds

The Milky Way is the galaxy that contains the Solar System.This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky. The term "Milky Way" is a translation of the Latin for "milky road", Via Lactea, in turn derived from the Greek kyklos galaktikos or "milky circle", "milk" also being the root for the Greek word for galaxy.



The galaxy has this appearance because it is a disk-shaped structure that is being viewed edge-on. Earth is located within the galactic plane of this disk, around two thirds of the way out from the center, on the inner edge of a spiral-shaped concentration of gas and dust called the Orion–Cygnus Arm. The concept of this faint band of light being made up of stars was proven in 1610 when Galileo Galilei used his telescope to resolve it into individual stars. In the 1920s observations by astronomer Edwin Hubble showed that the Milky Way was just one of around 200 billion galaxies in the observable universe.

The Milky Way is a barred spiral galaxy 100,000-120,000 light-years in diameter containing 200–400 billion stars. The galaxy is estimated to contain at least as many planets, 10 billion of which could be located in the habitable zone of their parent star. Depending on its structure the entire galaxy has a rotational rate of once every 15 to 50 million years. The galaxy is also moving at a velocity of 552 to 630 km per second, depending on the relative frame of reference. It is estimated to be about 13.2 billion years old, nearly as old as the Universe. The Milky Way is part of the Local Group of galaxies.

Stonehenge is a prehistoric monument located in the English county of Wiltshire, about 2.0 miles (3.2 km) west of Amesbury and 8 miles (13 km) north of Salisbury. One of the most famous sites in the world, Stonehenge is composed of a circular setting of large standing stones set within earthworks. It is at the centre of the most dense complex of Neolithic and Bronze Age monuments in England, including several hundred burial mounds.



Archaeologists believe the iconic stone monument was constructed anywhere from 3000 BC to 2000 BC, as described in the chronology below. Radiocarbon dating in 2008 suggested that the first stones were erected in 2400–2200 BC, whilst another theory suggests that bluestones may have been erected at the site as early as 3000 BC .

The surrounding circular earth bank and ditch, which constitute the earliest phase of the monument, have been dated to about 3100 BC. The site and its surroundings were added to the UNESCO's list of World Heritage Sites in 1986 in a co-listing with Avebury Henge monument. It is a national legally protected Scheduled Ancient Monument. Stonehenge is owned by the Crown and managed by English Heritage, while the surrounding land is owned by the National Trust.

Archaeological evidence found by the Stonehenge Riverside Project in 2008 indicates that Stonehenge could possibly have served as a burial ground from its earliest beginnings.The dating of cremated remains found on the site indicate that deposits contain human bone material from as early as 3000 BC, when the initial ditch and bank were first dug. Such deposits continued at Stonehenge for at least another 500 years.

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Atlantis is a legendary island first mentioned in Plato's dialogues Timaeus and Critias, written about 360 BC.

According to Plato, Atlantis was a naval power lying "in front of the Pillars of Hercules" that conquered many parts of Western Europe and Africa 9,000 years before the time of Solon, or approximately 9600 BC. After a failed attempt to invade Athens, Atlantis sank into the ocean "in a single day and night of misfortune".

Scholars dispute whether and how much Plato's story or account was inspired by older traditions. In Critias, Plato claims that his accounts of ancient Athens and Atlantis stem from a visit to Egypt by the legendary Athenian lawgiver Solon in the 6th century BC. In Egypt, Solon met a priest of Sais, who translated the history of ancient Athens and Atlantis, recorded on papyri in Egyptian hieroglyphs, into Greek. Some scholars argue Plato drew upon memories of past events such as the Thera eruption or the Trojan War, while others insist that he took inspiration from contemporary events like the destruction of Helike in 373 BC or the failed Athenian invasion of Sicily in 415–413 BC.

The possible existence of a genuine Atlantis was discussed throughout classical antiquity, but it was usually rejected and occasionally parodied by later authors. Alan Cameron states: "It is only in modern times that people have taken the Atlantis story seriously; no one did so in antiquity". The Timaeus remained known in a Latin rendition by Calcidius through the Middle Ages, and the allegorical aspect of Atlantis was taken up by Humanists in utopian works of several Renaissance writers, like Francis Bacon's "New Atlantis". Atlantis inspires today's literature, from science fiction to comic books to films. Its name has become a byword for any and all supposed advanced prehistoric lost civilizations.

The Bermuda Triangle, also known as the Devil's Triangle, is a region in the western part of the North Atlantic Ocean where a number of aircraft and surface vessels reportedly disappeared under mysterious circumstances.

Popular culture has attributed these disappearances to the paranormal or activity by extraterrestrial beings. Documented evidence indicates that a significant percentage of the incidents were inaccurately reported or embellished by later authors, and numerous official agencies have stated that the number and nature of disappearances in the region is similar to that in any other area of ocean.

The boundaries of the triangle cover the Straits of Florida, the Bahamas and the entire Caribbean island area and the Atlantic east to the Azores. The more familiar triangular boundary in most written works has as its points somewhere on the Atlantic coast of Miami; San Juan, Puerto Rico; and the mid-Atlantic island of Bermuda, with most of the accidents concentrated along the southern boundary around the Bahamas and the Florida Straits.

The area is one of the most heavily traveled shipping lanes in the world, with ships crossing through it daily for ports in the Americas, Europe, and the Caribbean Islands. Cruise ships are also plentiful, and pleasure craft regularly go back and forth between Florida and the islands. It is also a heavily flown route for commercial and private aircraft heading towards Florida, the Caribbean, and South America from points north.

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The Colosseum is an elliptical amphitheatre in the centre of the city of Rome, Italy, the largest ever built in the Roman Empire. It is considered one of the greatest works of Roman architecture and Roman engineering.

Occupying a site just east of the Roman Forum, its construction started in 72 AD under the emperor Vespasian and was completed in 80 AD under Titus, with further modifications being made during Domitian's reign (81–96). The name "Amphitheatrum Flavium" derives from both Vespasian's and Titus's family name (Flavius, from the gens Flavia).

Capable of seating 50,000 spectators, the Colosseum was used for gladiatorial contests and public spectacles such as mock sea battles, animal hunts, executions, re-enactments of famous battles, and dramas based on Classical mythology. The building ceased to be used for entertainment in the early medieval era. It was later reused for such purposes as housing, workshops, quarters for a religious order, a fortress, a quarry, and a Christian shrine.

Although in the 21st century it stays partially ruined because of damage caused by devastating earthquakes and stone-robbers, the Colosseum is an iconic symbol of Imperial Rome. It is one of Rome's most popular tourist attractions and still has close connections with the Roman Catholic Church, as each Good Friday the Pope leads a torchlit "Way of the Cross" procession that starts in the area around the Colosseum.

The Great Pyramid of Giza (called the Pyramid of Khufu and the Pyramid of Cheops) is the oldest and largest of the three pyramids in the Giza Necropolis bordering what is now El Giza, Egypt. It is the oldest of the Seven Wonders of the Ancient World, and the only one to remain largely intact. Egyptologists believe that the pyramid was built as a tomb for fourth dynasty Egyptian Pharaoh Khufu (Cheops in Greek) over an approximately 20 year period concluding around 2560 BC. Initially at 146.5 metres (480.6 ft), the Great Pyramid was the tallest man-made structure in the world for over 3,800 years. Originally, the Great Pyramid was covered by casing stones that formed a smooth outer surface; what is seen today is the underlying core structure. Some of the casing stones that once covered the structure can still be seen around the base. There have been varying scientific and alternative theories about the Great Pyramid's construction techniques. Most accepted construction hypotheses are based on the idea that it was built by moving huge stones from a quarry and dragging and lifting them into place.

There are three known chambers inside the Great Pyramid. The lowest chamber is cut into the bedrock upon which the pyramid was built and was unfinished. The so-called Queen's Chamber and King's Chamber are higher up within the pyramid structure. The Great Pyramid of Giza is the only pyramid in Egypt known to contain both ascending and descending passages. The main part of the Giza complex is a setting of buildings that included two mortuary temples in honor of Khufu (one close to the pyramid and one near the Nile), three smaller pyramids for Khufu's wives, an even smaller "satellite" pyramid, a raised causeway connecting the two temples, and small mastaba tombs surrounding the pyramid for nobles.