Dippy the dinosaur has welcomed visitors at the entrance of the National History Museum for over 30 years now. He is about to be replaced by a 82-foot blue whale skeleton, an honour to the biggest animals to ever have lived on Earth. Some 80 million items are five nicely curated collections (botany, entomology, mineralogy, palaeontology and zoology), set inside an incredible building, sometimes called the Cathedral of Nature. Entrance is free, but expect long queues.