The number of results after doing a quick search here the for "MBK intersection" made me wonder if I wasn't in somewhat of a rut, but I don't think so; it's a central spot that's provided a lot of entertainment for me in Bangkok, sometimes come upon unexpectedly - such as the break dancers at the National Stadium BTS. It's less than five minutes from the Hua Chang riverboat stop, the Jim Thompson silk house (something we haven't covered yet, but will eventually), as well as the prime shopping malls and funky little Siam Square (same same - I'm still gathering photos of it).
As you've already seen in posts and images showing the area (both day and night) it's a huge interchange from the pedestrian's perspective, and there's no way a sane person would want to try to cross it in any direction on foot at street level. In fact, there are barricades that would prevent it to save accidents and the scraping up afterwards. However, there are elevated walkways that take you in almost all directions, after you've climbed the stairs to get to them.
One night this last trip I was out on an evening walk, and while enjoying the comfortable evening breeze (tempered by the slightly acrid smell of the traffic) I found myself at a crosspoint and tried a few photos with a flash to see if I could capture it. The result of four of those is up top today, although the flash is a bit harsh on the girls walking in the center.
At the far left you can see the almost constant traffic there - one good reason not to cross any of the four directions on foot - and closer to the center are the green Mah Boon Krong Center logo initials. To the right the crossing leads to another junction where you can veer left and go up another half-flight of stairs into the huge ant farm that is MBK.