On your day in London, you might like to visit the British Museum, a museum of human history and culture. To find the exhibits you want to see while visiting, take an online tour of the highlights of the museum, an online tour of the cultures featured in the museum, and an online tour of the galleries.
Founded in 1753, the British Museum highlights include the Rosetta Stone, key to the deciphering of hieroglyphs; the Elgin Marbles in the Duveen Gallery, the orginal sculptures from Athens' Parthenon; elements from two of the Seven Wonders of the Ancient World, the Mausoleum of Harlikarnassos and the Temple of Artemis at Ephesus; and fabulous gold and silver Oxus Treasure from ancient Persia.
It is free of charge and open from 10 a.m. until 5:30 p.m. The museum is located on Great Russell Street. This site shows a diagram of the upper floor. For more information, try this Wikipedia article.