The summary document of a UN World Tourism Organization, Forum Barcelona 2004, says that the Toledo Monumental (Monument) in Spain is a good example of combining the goals of conservation and accessibility at a cultural or historic site.
I searched the main tourist information website for Spain, in English, and at first did not find anything to indicate that Toledo was particularly accessible to wheelchair users. After a few tries, I found that searching for "disabled persons Toledo" got a few results, but not as long a list as I had expected.
Travellers Howard L. Chabner and Michele E. DeSha have posted a trip report from their 2004 exploration of Spain. It sounds like Howard uses a power wheelchair all of the time, and that Michele and he travelled as a couple for this trip. They were able to enjoy strolling around Toledo and visiting several historic attractions. Their report is specific about the twists and turns.
In 2004, Chabner and DeSha stayed in the 4-star hotel, Hotel San Juan de los Reyes and were pleased with it. Again, their report is very detailed about the hotel.
The website link for the hotel has been updated. On the hotel's website it says that two of the junior suites have been adapted for handicapped use.
Visitor reviews on the Venere.com website are generally positive about the hotel. The guests occasionally repeat that the underground parking is very convenient.
If you have questions or comments about accessible travel, in Spain or anywhere, please do let me know. I love to read your stories!