I'll have some time on my own in Barcelona and Madrid before & after a RS tour. Aside from the typical tourist attractions, I like to find unusual (but safe) things to do that are off the beaten path. For example, I visited (and liked) the Cappucin Crypt in Rome (monk bones), the Science Museum in Florence (Galileo's finger), the Sewer Museum in Paris, saw an organ concert at Westminster Abbey in London, and visited mummies in St. Michan's church in Dublin. Upon reflection, they tend to fall in the morbid category, outside my usual comfort range, but still fun in the end.
Any interesting ideas out there? I'll be there in April/May. I'd also take suggestions for Segovia, Toledo, Granada, Tarifa, Arcos de la Fronterra, and Seville.
PS I did try searching the archives, following Kent's instructions, but was foiled. Does anyone know why the search results sometimes bring up the "classic view" results (difficult to find answers in)?