On Tuesday, Queen Elizabeth II surprised the audience by attending the opening ceremony of a long-awaited train line in London. The monarch donned a bright yellow suit and bonnet while visiting the Elizabeth line, which was named for her.

She was given a pre-paid Oyster travel card during the ceremony on Tuesday at Paddington station in west London, but she did not use it. The Queen was welcomed by British Prime Minister Boris Johnson and London Mayor Sadiq Khan, together with her son, Prince Edward.

The 96-year-old queen has been plagued by mobility concerns and has had to cancel many public engagements in recent months, including the opening of Parliament last week. The monarch must open Parliament because it is a fundamental constitutional function. The Queen had to assign that obligation to the state counselors, Charles, Prince of Wales, and William, Duke of Cambridge. The Elizabeth line, dubbed Crossrail while it was being built, is significantly larger than the city’s current “Tube” lines. On May 24, the first stage will be open to the public.

The 62-mile network is centered on a core of 26 miles of brand-new tunnels running through central London, burrowed with astonishing accuracy beneath one of the world’s most densely populated cities.
Crossrail was Europe’s largest engineering project at the time of its development. The twin tubes, which are 20 feet in diameter and up to 40 meters (130 feet) deep, snake their way past building foundations, London Underground tunnels, and a plethora of other buildings and services.