Two main reasons:
Most European cities are built on rivers, so there are far too many to mention. Name almost any major European city and it will have a river or rivers running through it.
So they could have a water source.
Most of Italy's ancient cities were built on the plains, near rivers. The ancient Italians were mostly farmers, so their cities were build in areas conducive to farming.
There are many factories built there because of it's many rivers to transport goods.
so they have enough water and so they think there cool to have a big river near them
The question is so broad it would mean naming hundreds through the world - impossible to do here. Such a question would need to be much narrower.
Rivers are not built. They occur naturally, so there is no year that the river Boyne was built.
Ireland's west coast is on the Atlantic Ocean. Ireland is a country of many rivers, mountains and lakes. Ireland has many rivers. The longest is the river Shannon, so it is important. It flows through many towns. The city of Limerick is built on the Shannon. Other important rivers include the ones that other main cities are built on. The capital city is Dublin and it is built on the river Liffey, and there are smaller rivers that flow into the Liffey in or close to the city. Cork is built on the river Lee, with some of the city being on an island in the middle of it. Galway is on the Corrib, a short river flowing from a lake of the same name. Belfast is on the Lagan. Derry is on the Foyle. There are many other important ones too. In terms of mountains, there are also many of them. Most are in ranges. Carrauntoohill, the highest mountain is in the Magillacuddy Reeks. Other important ranges include the Wicklow mountains, the Mourne Mountains, the Twelve Pins. There are also many others.
Because in older times trade was done via boats therefore the bigger trade cities had to be near rivers so the boats could come up the rivers from the sea.
There was no one Pueblo people. Many tribes built pueblos, in what is now New Mexico, Arizona, and Texas, so there were many rivers located near their settlements.
They were built by rivers so they could go to other places to trade goods so they could sell the goods they got in there town for money than they paid for it.
Easy access to water (a basis for life - be it drinking, bathing or irrigation for crops). The rivers also provided an efficient (relatively fast and secure) way of transporting trade goods between different towns.