One of my favorites is located in the Umeda Sky Building observatory from Osaka, at the Lumi Deck, a place reserved for lovers where you hold your partner's hand and touch a button on the seat and the floor lights up with the shape of a heart. (^_^) Then, you can engrave a heart lock with your and your partner's name and the lock can be locked on a "Fence of Vows", as you can see in the photo... of course, to secure your love (^_^). A nice custom which reminds me of something similar seen in Europe, on the streets of Vilnius...
EXIF info:
Nikon D90
Lens: VR 18-55mm F/3.5-5.6G
Focal Length: 55mm
Aperture: F/6.3
Shutter Speed: 1/320s
ISO Sensitivity: ISO 200