This is Belfast, one of the great cities of the industrial revolution, and home to Thomas and Dervla O’Hare. They’ve lived here for 18 years, and although they still love their tiny cottage for its compactness, they’re about to build something much, much bigger. They’re building a 21st century answer to the Roman villa, with a copper roof, glass and concrete walls and vast amounts of living space all arranged around a central courtyard.