Short answers, pulled from the story.
The Natural History Museum in London holds approximately 80 million specimens across five main collections: botany, entomology, mineralogy, palaeontology, and zoology. Many items in these collections have significant historical as well as scientific value.
The Natural History Museum opened on the 18th of April 1881, though the full move of collections from the old British Museum in Bloomsbury was not completed until 1883. The Alfred Waterhouse building had been under construction since 1873.
Alfred Waterhouse designed the building's facades in an idiosyncratic Romanesque style, inspired by his frequent visits to the Continent. He took over the project in February 1866 after the original competition winner, Captain Francis Fowke, died in December 1865.
Dippy, a 105-foot-long Diplodocus carnegii replica, was removed in early 2017 after 112 years on display and replaced by the skeleton of a blue whale nicknamed Hope. Hope is the actual 128-year-old skeleton of a whale that stranded near Wexford Harbour, Ireland, in March 1891.
The Scottish-American industrialist Andrew Carnegie donated the Diplodocus cast after a conversation with King Edward VII. Carnegie paid £2,000 for the casting, and the exhibit was unveiled on the 12th of May 1905. Carnegie later paid for additional copies to be displayed in major European capitals and in Central and South America.
Archie is an 8.62-metre giant squid taken alive in a fishing net near the Falkland Islands in 2004, housed in the Darwin Centre's Phase 1 building. It is preserved in a 9.45-metre acrylic tank using a mixture of formalin and saline solution and is not on general display; visitors may view it on a paid Spirit Collection Tour.