Marie and I took a ferry down the Thames to Greenwich.  I'm really glad we went to Greenwich as the river trip was gorgeous, and the buildings and museums at Greenwich were interesting.  I had actually wanted to go to Portsmouth to see the Mary Rose, the Henry VIII's ship which sank in 1545.  She was raised in 1982 and is being restored as a museum.  She seemed to suddenly capsized, leaving many Tudor artifacts that provide insights into the Tudor period.  However, Portsmouth is about a 3 hour train ride from London, and Greenwich was an hour and a half long cruise down the Thames.  So we opted for Greenwich.  Greenwich is the home of the Royal Observatory, from which all time is counted (Zulu time for you military folks).  It was way on top of a steep hill, so we didn't make it to the Observatory.  But  there are plenty of interesting things to see in Greenwich.