Designed by Sir Christopher Wren and opened in 1694 as the Royal Hospital for Seamen, few would argue that the Old Royal Naval College is Wren’s riverside masterpiece in Greenwich. Just don’t overlook the interior. Described as the “Sistine Chapel of the UK,” the Painted Hall is the greatest piece of decorative painting in England and the largest painted interior in Europe. Created in the 18th century by Sir James Thornhill, the epic painted ceiling recently reopened after a multimillion-pound conservation effort. The paintings celebrate England’s naval power and mercantile prosperity as well as its monarchs and other historical figures. On the first Wednesday of every month, the venue offers a “Pay as you wish Wednesday,” giving visitors the chance to take a tour with access to the Painted Hall and pay what they want.