A newcomer to the Phoenix area asks why so many residential developments in the city and its neighboring cities and towns have big masonry block walls around homes rather than the fences or lack of property barriers that are common in other parts of the country. Among the experts with an answer is Barzin Mobasher, a Fulton Schools civil engineering professor and an expert on building materials and their structural stability. The strength of block walls along with the variety of creative architectural features they can offer is one reason those walls became popular with builders, Mobasher says. Another factor: Much of the technology for making masonry blocks was developed in the Phoenix area, he says, which led to masonry plants being built in the area, which then drove the market for use of concrete blocks in home construction.