Woodlice have probably been living in the Wardrobe Tower for as long as it has been standing. Standing is rather an optimistic term given what remains; a weathered shard of wall, like a solitary wisdom tooth. But to the woodlice it is still home. Strange creatures, they live in the boundaries that mark our rooms whilst the spaces we occupy are the edge of their realm. They crawl out from cracks when it rains, as if marching to the drumbeat of the drops. When the sun shines they once again seek cover deep beneath the mortar. Aliens share our architecture.

Vesuvius is the cradle of civil engineering. Successive violent eruptions pumped out rich, thick deposits of minerals, covering the landscape, each a variation of the last. Green pumice, red pumice, brown tuff, grey tuff, ash, lava, clay; a geological Jackson Pollock. Humans flocked to the fertile soil and happily built settlements, until the volcano spat once again. But each eruption brought opportunity, and as the next pioneers walked in they fused new combinations of the earth under their feet. Ceramics and cements developed in proto-industry. Burnt limestone mixed with hot ash mixed with wet earth. Fizzing, popping, pozzolana. Reactions balanced millennia later, recipes learnt through trial and error. What the volcano gave the Romans, the Romans gave the world. Geochemical architecture. Their opus magnum: concrete.

A provocative question: Why waste time caring for old buildings? Many remain as symbols of yesterday's elite. Many stand as enduring symbols of inequality. They are decaying decadence. How can the socially aware architect allow themselves this luxury? Similar skills could protect vital technical infrastructure from changing climate. Efforts could be spent finding solutions to the perilously uneven distribution of housing. Here I will justify this as a legitimate struggle.

Bosra was half-way between Amman and Damascus. I sat next to an engineer on the bus. He was from Yemen, studying in Syria. I told him I was an architect, studying in England; I'd come to see the stones of Syria. He told me about skyscrapers made of earth in Yemen. he even gave me a key-ring showing one. He understood why I was getting off at Bosra, in the middle of the desert, right on the border between Jordan and Syria, but some others on the bus eyed me suspicously. People in Amman had already told me that visitor numbers were down since the war had started in Iraq.