Just about every building in Thailand has a spirit house to go with it. It's a pre-Buddhist tradition emphasising that the land is not ours. We therefore have to take care of the land and make offerings to the spirits of the land. The little house is a place for PHRA PHUM, the spirits of the land, to live in.
Theoretically, the encourage the spirits to live there, you make offerings every day - offerings of food, water, sweet-smelling incense/joss sticks, etc.
Inside the little 'house' are ceramic - these days sometimes plastic - figures representing the 'guardian spirits'. Offerings are made in small jars, glasses, etc.
Hope this sort of explains it. To me, it's more than a 'romantic' idea - it's a daily reminder of how we, as human beings, are here and living because of the earth. Whether you believe in God, in some kind of animism, or even if you're an out and out atheist, it seems to me that the rituals associated with spirit houses are (in microcosm) symbolic of the way we live on earth.
Sorry to be so 'serious' - it's late at night at the moment, but it does explain something of my interest in spirit houses (especially the spirit houses erected by people - unlike me - who actually believe in the rituals that they perform).
nice composed! so colorful with great details! i'd be very grateful if you explained about the stuff in front, i mean that glass of water and the bowl full of flowers! well done Len!