London extended about a mile along the Thames and about half a mile inland. It had narrow twisting lanes, some with a ditch down the middle for water runoff. Most of its houses were two stories, the ground floor having booths and workshops, and the upper floor living space. Most of the houses were wooden structures. The richer merchants' and knights' houses were built of stone. Walls between houses had to be stone to a height of 16 feet and thatched roofs were banned because there had been many fires. There was poor compliance, but some roofs were tiled with red brick tiles. The population was about 40,000. There were over 126 churches for public worship, thirteen monasteries (including nunneries), and St. Paul's Cathedral. All were built of stone. The churches gave a place of worship for every 300 inhabitants and celebrated feast days, gave alms and hospitality to strangers, confirmed betrothals or agreements of marriage, celebrated weddings, conducted funerals, and buried the dead. The synod of Westminster of 1175 prescribed that all marriages were to be performed by the church. A bare exchange of words was sufficient to constitute a marriage. Church law required a warning prior to suspension or excommunication. Monastic, cathedral, and parish schools taught young boys grammar so they could sing and read in church services. Nuns taught girls. Fish but no meat was eaten on Fridays. There was dark rye bread and expensive white wheat bread. Vegetables included onions, leeks, and cabbage. Fruits included apples, pears, plums, cherries, and strawberries. Water was obtained from streams running through the town to the Thames and from springs. Only the rich, palaces, and churches could afford beeswax candles; others had homemade tallow [cow or sheep fat] candles which smelled and gave off smoke. Most people washed their bodies. Even the poor had beds and bed clothes. The beds were often shared. Few babies survived childhood. If a man reached 30, he could expect to live until age 50. Thousands of Londoners died during a hot summer from fevers, plague and the like. In London, bells heralded the start and finish of all organized business. The sellers of merchandise and hirers of labor were distributed every morning into their several localities according to their trade. Vendors, craftsmen, and laborers had their customary places. Some vendors walked the streets announcing their wares for sale. There were craft guilds of bakers, butchers, cloth workers, and saddlers, as well as of weavers. Vendors on the Thames River bank sold cooked fish caught from the river and wine from ships and wine cellars. Cook shops sold roasted meats covered with hotly spiced sauces.