Benefits of a large lens aperture

This is the remarkable interior of the mausoleum built for Tamerlane -- or Timur the Lame -- the 14th century conqueror of Central Asia, India, and as far north as Moscow. It is lit beautifully and dramatically, and the symmetry, ornate design, and attention to detail is stunning. The ceiling graphic is a square, but I photographed it with a Sigma14mm wide angle lens from one of the corners, thus creating a diamond effect. My settings were 1/125, f/1.8, and 1250 ISO. Note the large lens aperture allowed me to use a fairly fast shutter with a reasonable ISO in this very dark interior. It is curious to me that a man who was directly responsible to murdering an estimated 17 million people -- 5% of the population of the Earth at the time -- was and is honored in such a manner.