The Romans fought many wars against other countries, and enjoyed watching violent sports. They enjoyed watching races between chariots pulled by horses, and fights between men using weapons (gladiators). Unlike in modern sports, the fighters were often killed in fights. Romans enjoyed these shows in the Colosseum.
The Romans had great civil engineering. They built many large public buildings and villas, aqueducts to carry water, stone bridges and roads. Some of these things can still be seen today. Many famous writers were Romans, including Cicero and Virgil.
The New Testament of the Bible tells about the Romans in the life of Jesus Christ. During Jesus' life, the Romans, who were pagans, ruled his country. Later, several emperors tried to destroy Christianity but they did not succeed. By 312 the emperor Galerius allowed people freedom to follow Christianity, and the next year, a general, Constantine, became emperor and converted to Christianity.
The city of Rome was taken over several times by barbarians, notably in 410 when the Goths sacked the city (looting). The last Western Roman emperor, Romulus Augustus, resigned in 476 . The Roman Empire would last another 1,000 years as the Byzantine Empire in the east.
The main coin of the Roman Empire was the silver denarius. Later denarii were smaller.
Various reasons have been given for the fall of Rome. Edward Gibbon wrote "The Decline and Fall of the Roman Empire" in which he investigated various ideas. Chief among them was (in his opinion) was the effect of Christianity on the ability of the Empire to defend itself militarily.
Other historians blame the unstable system of leadership. In a 50-year period, only 2 out of 22 emperors died a natural death. Most of the emperors were assassinated.
Regime
A regime is the leader and other people who run a government of a sovereign state.
There are many kinds of regimes. They can achieve power in many ways. Depending on the time and place and local civics like the electoral system, they can lose power in many ways too. The most common way for a regime to lose power was a coup, invasion or revolution until the 20th century. After that it became very dangerous and difficult to use these methods. Peaceful regime change is usually by an election - this method is now used by more than half the people on the Earth. It is called representative democracy. Such regimes are often called administrations to make it clear they are not dictators, and since the executive branch does not have all the power itself - it may share it with a legislative branch. Also the judicial branch is separate. The courts are not usually considered part of the regime.
However, some things are the same no matter how the regime achieved power:
When many regimes negotiate at the United Nations or World Trade Organization, it does not matter at all how each regime got its power. It matters only that they can agree and make everyone in their country do as the agreement says.
When someone wants a regime to change in another country, they usually are not able to do this by any means other than violence or interfering in its election. This is common if a regime is threatened by another regime.
River
A river is a stream of water that flows through a channel in the surface of the ground. The passage where the river flows is called the river bed and the earth on each side is called a river bank. A river begins on high ground or in hills or mountains and flows down from the high ground to the lower ground, because of gravity. A river begins as a small stream, and gets bigger the farther it flows.
The start of a river is called the "source" or "head water". The part of the river that is near the source is called a 'young' river. A young river is often in a V-shaped river bed, and flows quickly downhill over stones, and around big rocks. Young rivers often have lots of small waterfalls and rapids. As the rivers travel downhill they begin to erode the ground taking small bits of soft rock and soil.
The middle part of a river is called a mature river. A mature river makes a riverbed that is U-shaped. It might be very deep and run fast. It sweeps over small rocks and boulders, and makes big turns around hills and mountains. It is much wider than a young river, but not as wide as an old river. To cross over a mature river, people use bridges. Many cities and towns are built on the banks of mature rivers. Many farms that keep animals such as dairy cows, horses and sheep are along mature rivers because the animals can drink from the river every day.
A river usually ends by flowing into an ocean, a lake or a bigger river. The place where the river flows out into a bigger body of water is called the 'mouth' of the river.
As a river flows towards its mouth, the countryside around the river often changes from hilly to flat. As it flows over the flat land the river becomes wider and slower. A wide slow river is called an 'old river'. An old river often floods across the land after there is lots of rain at the headwaters. An old river slowly builds up its banks on either side; the high banks are called levees. An old river often meanders (twists and turns), and sometimes, after a flood, it leaves lakes behind which are called ox-bows or billabongs. Old rivers are the most useful type of river for growing crops. Corn, rice, fruit, cotton, hay, tobacco and sugar are some of the crops that are grown near old rivers.
The shape of the mouth depends on the conditions of the sea where it flows. If there is a strong tide where the river meets the sea, the river forms an estuary. An estuary is a wide, funnel-like mouth of the river. The fresh water of the river mixes slowly with the salt water, becoming brackish water – somewhat salty water. Many kinds of fish, clams, molluscs and other sealife live at estuaries. Many of the world's largest cities and harbours are at estuaries.
Where a river flows out to the sea, it sometimes flows very slowly through sandy or muddy land, making lots of little islands as it flows. The main stream of the river gets broken into many parts that spread out into a triangle shape like the Greek letter delta. When this happens, it is called the delta of the river. Deltas are often places that are not good for towns or farms but are very good for birds and other wildlife and fishing. Deltas are often made into wildlife reserves. Not all rivers have deltas. There are deltas on the Nile River, the Amazon River, the Mekong River, the Mississippi River and the Danube River.
Some rivers flow underground through caves. Underground rivers form in places where there are lots of cracks in the rocks above, so that in rainy weather, the water runs downs and collects in small underground streams. Sometimes the underground water trickles or gushes out of the ground to form a small spring of water. In other places, where there are caves, the small underground streams run together to form a river. The river can sometimes run through deep wide underground caverns. While many underground rivers flow gently, some underground rivers flow fast and have rapids, particularly after heavy rain. Many underground rivers flow out through a cave mouth to become an ordinary river.
The water in rivers is "fresh water" that has come from rain, snow and from underground streams. It can usually be drunk safely by people unless it is too dirty because of mud or human pollution. People and animals need fresh water to drink, so they often live by the side of a river.
Right angle
A right angle is an angle with a measurement of 90 degrees. When two lines cross each other so that all the angles have the same size, the result is four right angles. The top of the letter T is at right angles to the vertical line. Walls of buildings are usually at right angles to the floor. Two things that are at right angles are called "perpendicular" or "orthogonal". This is expressed using the formula_1 symbol (such as in formula_2).