Edward Montagnino, Age 13, Stratford, Conn., for his question:     

How are the houses of Venice built on the water?     

The Italian city of Venice seems to rise up frm the floor of the sea. Its Streets are canals, and its taxicabs are graceful boats ca11ed gondolas. Handsoene Bridges span the canals, and exquisite buildings reflect in the water. The city, Hundreds of years old, seems to float on the water, and you wonder what keeps its Sturdy palaces from sinking.     The story of Venice began some 1500 years ago when barbarian vandals poured down into Italy from northern Europe. Towns were pillaged and produce was plundered. In most places, the city and country people alike were at the mercy of the invaders.     There were, however. Some who remembered a place to retreat, a secret place that might be safe.  They fled northward along the shores of the Adriatic Sea. This body of blue water is an arm of the Mediterranean which separates the eastern coast of Italy from  Yugoslavia. The River Po and the River Piave empty into the northern arch of the Adriatic creating sea washed sand bars and muddy islands. These low, flat islands became a refuge barn the barbarian invaders. The people drove wooden pilings into the muddy islands and topped them with platforms to support their rickety houses. It was a life of hardship, but as time went on the island dwellers learned to improve their conditions. In the year 452 a.d. They established themselves as a city. The buildings became stronger, and the waterways became canals to connect one populated island with the next.     'The city which started in fear and hardship prospered. It served as a retreat to keep out the European barbarians, and through the centuries it served to keep out invaders again and again. The people were governed by their elected doge or dlike and refused to be taken over by outside powers. Their trade routes led north into Europe.     And ships rested in the city's harbor between trips to the orient.  The merchants of Venice became rich, and art flourished in the watery city. Wealth was spent on buildings, and the islands became crowded with elegant palaces and sturdy churches. Museums and libraries reflected their graceful walls in the canals, and all this architecture was constructed on 120 or so soft, muddy islands. It was built, as were the first houses of Venice, on pilings driven deep into the mud.     The city of Venice is traversed by 170 canals which serve as its streets and avenues. The canals are spanned by almost 400 graceful bridges. You can walk across the bridges and along the narrow paths that border the buildings, but you still cannot drive a car or an army of tanks down the watery streets of venice.