Abandoned Building in Japan

I was biking near the Tamagawa River yesterday, and we went inside a park complex that includes Neko Tama and Inu Tama, which are like poor man's zoos with only domestic cats and dogs. Towards the back, there are two giant European-style houses made from stone, completely abandoned. There were no signs, but from what I could deduce, they were built in the 19th century for British occupants. Very interesting thing to see in the middle of surburban Tokyo, but I guess they can't demolish stone buildings as easy as they can wood-construction. The one pictured above seems to have been used as an office building until quite recently.