What did these headquarters castles look like? The builders of castles began to emphasize curtain walls and towers rather than a single great tower, and so the castle became an “enclosure” castle or enceinte. The garrison had more space, so the castle could assume a greater role in the offense. For example, during sieges the garrison used their own hurling machines to fire missiles back at the attackers. When the terrain permitted, rectangular ground plans replaced the irregular plans of the twelfth-century castles. Walls became higher and thicker, and the masonry spread outward at the bottom to form a sloping “talus” that prevented the effective use of battering rams or mining. At the top of the wall, stone machicolations replaced wooden hoardings, and tile roofs might even cover the wall-walks. Wall and corner towers became inde pendent strongholds although some were built as half cylinders with an open back to prevent an enemy from using a captured tower against the garrison. The top of the tower might be flat and used as a firing platform, or it might be covered with a conical roof (compare Figures 11 and 17). Sometimes, to save costly materials and the builders’ time, turrets known as “pepper pots” replaced towers on the upper wall. Around the castle, doubled encircling walls created open spaces known as lists (see Figure 13). Lists made convenient places for the garrison to exercise and train and for archers to practice (Document 63). In times of peace the knights held mock battles, or tournaments, in the lists, and townspeople held markets and fairs. In wartime the garrison set up their stone-throwing machines, and peasants and townspeople took refuge in the lists. The castle had to accommodate several functions within its walls: a magnificent great hall with ample space to hold court and serve state banquets (as well as impress and intimidate visitors); huge barns to store grain; stables and shelters for animals; lodging for workers; and all manner of workshops. The heavily fortified and residential gatehouse, where the governor of the castle could live and also direct an active defense of his castle, replaced the single great tower. Nevertheless, the great tower survived as a symbol of power, as seen at the Earl Marshall’s castle of Pembroke in Wales (see Figure 3) or the French royal castle of the Louvre in Paris.