The people of Venice are continually affected by the water that surrounds them. The water influences their food and housing as well as their mode of transport. For example seafood is the main course of a typical Venetian meal. Houses and other buildings do not stand on solid ground but on wooden piles (posts) driven into the mud. Almost all Venetians are Roman Catholics. Since about 1950 thousands of Venetians have left the islands to live in the mainland communities of Marghera and Mestre. They have moved chiefly because the mainland offers greater job opportunities and a lower cost of living. The modern apartment buildings in these communities also attract many Venetians. Most of the buildings on the islands were erected hundreds of years ago and there is no room to build new housing.