Why it looks like this

For its first eighty years as capital (from 1782), Bangkok moved by water: canals called khlongs were the streets, and houses faced the water. The first paved road, Charoen Krung, was built only in 1864 at the request of foreign traders.

Roads came late and were laid sparsely over orchard and paddy land, so the city developed its signature pattern: huge blocks served by sois — long, narrow lanes, many of them dead ends — branching from a few main roads. Many canals were later filled in and became roads themselves.