An ancient monument that would challenge today's builders, and a monstrous modern blob.
My wonder is the Great Pyramids at Giza. Built 5000 years ago, they remain the largest and heaviest stone monuments in the world, and still manage to fascinate. I'm intrigued about how on Earth they built them. Single blocks weighing up to 70 tonnes are each placed as accurately as any modern techniques today would allow, forming near-perfect mathematical symmetries we would struggle to imitate.

From a construction manager's perspective, the sheer logistics and buildability of the pyramids are mind-bogglingly complex. Many theories exist about how they were built, but none seems convincing. I wouldn't have minded sitting on the interview panel with Tutankhamun assessing the bids from the local builders.

My blunder is the Tricorn Centre in Portsmouth. It's a car park, shopping centre, a series of public lavatories and a monstrous concrete blob in the town centre. I grew up close to Portsmouth and have often wondered what people entering the UK through the ferry terminal there must think of our country when faced with the Tricorn. It should be demolished.