Kyoto, surrounded on three sides by mountains, is known for its cold winters and hot summers. In the days before air conditioners, people devoted a lot of time and energy to beating the summer heat, and one of the things they came up with is the elegant custom of kawadoko, riverside dining.
If you walk along the Kamo-gawa River in central Kyoto, you will see a lot of restaurants with platforms built out over the side of the river where patrons go to get cool and enjoy food or drinks. Another famous place is Kibune, a tiny village north of Kyoto. There’s a long, winding river through a ravine with a lot of old, high-class Japanese inns and kawadoko restaurants.
I went there a couple of years ago, and the kawadoko restaurants were a little pricey for me, but it was a really nice place for walking and taking photos.
There are some excellent descriptions on these blogs and websites:

Gaijin Report: http://www.hotwire.jp/repo/vol4.html (general overview)
Secret Japan: http://www.secret-japan.com/forum/viewtopic.php?p=220 (general guide to Kibune and nearby Kurama Onsen)
Kibune official site: http://kibune.jp/ (Japanese only)
Google Maps: http://www.google.co.jp/maps?f=q&source=s_q&hl=ja&geocode=&q=%E8%B2%B4%E8%88%B9%E3%83%90%E3%82%B9%E5%81%9C&sll=35.104392,135.767498&sspn=0.048872,0.069437&ie=UTF8&ll=35.113485,135.763378&spn=0.024433,0.034719&t=h&z=15

Getting there:
From Kyoto’s Sanjo Station, take the Keihan Honsen Tokkyuu (Limited Express) bound for Demachiyanagi Station. Change to the Eizan Dentetsu Honsen (Eizan Railway Main Line) bound for Anba. Get off at Kibune Guchi Station. It takes about 36 minutes from Sanjo Station, and the fare is 620 yen. From there, you can walk about 1.3 km or take the bus. The bus schedule is here. It’s in Japanese, but the two columns on the left are for weekdays and the two on the right are Sat., Sun., hol. (departure from Kibune Guchi on the left and return on the right) . The buses only run on weekends from around Dec. 8 until Shunbun no Hi (First day of Spring, around Mar. 20). The fare is 160 yen.

Here’s a Google Earth view of the area (click to enlarge):

Kibune map