attackers. However, some plaster has been found with blood, bone remains, gold dust, oil, and straw mixed in. Some of these materials were functional, adding strength, while others had spiritual meanings, possibly to defend against evil spirits. Benin City in particular had sophisticated house and urban planning. Houses had several rooms and were usually roofed, enclosing private quarters, sacred spaces, and rooms for receiving guests. Usually, multiple houses would enclose a shared courtyard. When it rained, the house roofs would collect water into a space in the courtyard for later use. Houses would have public frontage along long, straight roads. The city had markets and the chief's palace in the center of the city, with dominant and subordinate roads leading outwards. HM Stanely, quoted in Asomani-Boateng, Raymond (2011-11), described the roads as "...fenced with tall [water cane] neatly set very close together in uniform rows..." possibly for privacy. More sophisticated construction methods include stone and brick constructions, with and without mortar, plaster, and accompanying defensive structures. Fired brick constructions were observed in settlements in northeast Nigeria, such as historic Kanuri buildings. Many of the bricks have since been removed for new constructions. Laterite block walls with clay mortar were found in northwest Nigeria, possibly inspired by Songhai constructions. Walls built from stone without mortar have been found where societies could obtain sufficient stone, most notably in Sukur. None of these constructions have been observed with additional plastering. The Sukur World Heritage Site is especially significant, with extensive terraces, walls, and infrastructure. Walls separate homes, animal pens, and granaries, while terraces often include spiritual items such as sacred trees or ceramic shrines. Early iron foundries were also present, usually placed close to the homes of their owners. Broadly, three styles of residential architecture can be identified in indigenous Nigerian architecture, relating to the people groups which developed them. Hausa architecture uses plastered adobe to create monolithic walls. Roofing is provided by shallow domes and vaults made from structural timber beams covered by laterite and earth. Homesteads are bounded by perimeter walls with both circular and linear interior divisions with one clearly defined entrance. Yoruba architecture uses cured earth walls to support roof timbers, over which leaf or woven grass roofing is applied. These walls are usually homogeneous mud structures, though wattle-and-daub techniques can be found in certain locations. Space is divided into individual units which are then connected by proximity and