My best idea so far. Museums. We went to the National Museum of Emerging Science and Innovation on Monday - and the Edo-Tokyo Museum yesterday (although neither day was particularly hot). Today was a bit** and we went to the Bridgestone Museum in the afternoon (the Bridgestone has great A/C ). Tomorrow we plan to go to the National Art Center (Pop Art exhibit) after lunch.

Most museums aren't very expensive. But you can get discounts if you have the Tokyo Handy Guide (which we got from the hotel concierge). Note that you need one booklet per person for discounts. There are also senior discounts at some places if you're > 65. The Edo cost us about 500 yen for 2 seniors (including audio guides).

The weather the next few days looks to be very hot (although cooler than in parts of Argentina - where it was > 40C this week - glad we came here and didn't go there!!!). So I'm sure people planning to visit during the hot weather will appreciate any and all ideas in addition to mine. Robyn