I think I might actually have walked through it while looking for the Old Siam Plaza. The sidewalk was all covered up and there were a lot of fabric vendors. I had a particular destination in mind because I am not that familiar with fabric, so I went to a place that was recommended in a guide book.

PS: On my last day in BKK, which happened to be a Sunday, I went to the store at the southwest corner of Asoke and Sukhumvit and the lady in the store told me they didn't sell Thai silk. I asked if any nearby places did but didn't get a good answer. The lady said that all the places that sold Thai silk were probably closed because it was Sunday, but she didn't indicate if any of them were nearby.