A defensive wall is a fortification used to protect a city or settlement from potential aggressors. In ancient to modern times, they were used to enclose settlements. Generally, these are referred to as city walls or town walls, although there were also walls, such as the Great Wall of China, Hadrian's Wall, and the metaphorical Atlantic Wall, which extended far beyond the borders of a city and were used to enclose regions or mark territorial boundaries. Beyond their defensive utility, many walls also had important symbolic functions — representing the status and independence of the communities they embraced.

Existing ancient walls are almost always masonry structures, although brick and timber-built variants are also known. Depending on the topography of the area surrounding the city or the settlement the wall is intended to protect, elements of the terrain (e.g. rivers or coastlines) may be incorporated in order to make the wall more effective.

Walls may only be crossed by entering the appropriate city gate and are often supplemented with towers. In the Middle Ages, the right of a settlement to build a defensive wall was a privilege, and was usually granted by the so-called "right of crenellation"^{[citation needed]} on a medieval fortification. The practice of building these massive walls, though having its origins in prehistory, was refined during the rise of city-states, and energetic wall-building continued into the medieval period and beyond in certain parts of Europe.

Lars Brownworth, an author and former United States history and political science teacher at The Stony Brook School, is the creator of the top 50 podcast, 12 Byzantine Rulers: The History of the Byzantine Empire. This podcast was created on a whim by Lars and his brother, Anders Brownworth. Often mistaken for a college professor, Lars was, in fact, a high school history teacher at the time the podcast was produced.

On August 15, 2007 Mr. Brownworth announced that he had resigned from teaching in order to work on a book with Crown Publishing titled Lost to the West: The Forgotten Byzantine Empire that Rescued Western Civilization, which was published on September 15, 2009. He is currently working on a new podcast about the history of the Normans as well as a book on the Macedonian Emperors of Byzantium. He maintains a blog called Finding History where he responds to reader and listener submitted questions.

In August 2011 Mr. Brownworth returned to the classroom at La Lumiere School, a coeducational boarding school in La Porte Indiana

For the Australian politician, see Bob Catley (Australian politician)

Robert Adrian 'Bob' Catley is a British musician, perhaps best known as the lead singer of the rock band Magnum. He is also an accomplished solo artist.

Born in Aldershot on 11 September 1947 Catley's family moved to the Tile Cross area of Birmingham when he was young. He went on to attend the nearby Central Grammar School and left to start an apprenticeship at the GPO before deciding on a musical career shortly after meeting similarly minded individuals at college. During this time he joined several bands, such as The Smokestacks (who also included drummer Kex Gorin, Life and Clearwater). His first professional band was when he joined local outfit The Capitol Systems. The line-up was Bob Catley (vocals) Paul Sargent (guitar) Charlie Harrison (bass) (replaced later by Dave Morgan), Dave Bailey (keyboards) and John 'Pank' Panteny (drums). Shortly afterward they changed their name to Paradox, inspired by a science-fiction novel. A one-off deal was arranged with Mercury after Paradox had come to the attention of Francis Rossi and Rick Parfitt--the tracks chosen were "Ever Since I Can Remember", backed with "Goodbye Mary". In addition they recorded "Mary Colinto" and "Somebody Save Me". All of these songs were written by Dave Morgan.

Phil Carmen (born Herbert Hofmann, February 14, 1953 in Montreal, Quebec) is a Swiss musician and producer of Canadian heritage.

Carmen grew up in Frankfurt am Main, Germany and in Lucerne, Switzerland. In Lucerne, he went to the Conservatory, but later studied bookkeeping. In 1975, he decided to turn to music. With bassist Mike Thompson, he founded the duo Carmen & Thompson, playing especially country music. The single "Time Moves On" reached #31 on the Italian charts in 1980, and in 1981 they appeared at the San-Remo-Festival performing the song "Follow Me".

After seven years of stage experience Phil Carmen founded the Picar Studios in Stein am Rhein, Switzerland in 1982 and recorded two solo albums which attracted little attention until 1985, when he had a hit with the LP Walkin' the Dog, which reached #3 in the Swiss charts. The single "On My Way in LA" was his greatest success and climbed in the summer of 1985 to #18 in Germany and #9 in Switzerland. "On My Way in LA" was also used in the television series Wild West in 1988. His 1986 album Wise Monkeys hit #1 on the Swiss charts, while the single "Moonshine Still" reached #10. His last successful album as a solo artist was City Walls (1987), which went to #10 in Switzerland. The corresponding promotional tour led to the Live in Montreux album with the same band line up of Brian Auger on organ, Pick Withers and Larry E. Van on drums, Dick Morrissey on sax, Steve Dawson on trumpet, Steve Evens on bass, and Sabine van Baaren, backing vocals.