Over the years, I have photographed many buildings at different times of the day.

Some of the most interesting and artistically appealing of these photos have been taken during what photographers call the 'blue hour'. This is that time, usually late dusk, when the sky becomes a rich, deep blue. At this time, there is still enough ambient light to pick out details of the buildings' exteriors, and (with meticulous planning!) the interior lights of the buildings appear to glow brightly, with some warmth in contrast to the cool sky colour.

This requires a few practical preparations. Firstly, there needs to be a safe place to put the tripod for a long period. This is for security of the equipment, and also to prevent accidents. There needs to be awareness of the best times of the evening (or morning) for the light to be just right. And there has to be a considerable time to take the shots, as a number of different exposures will be required - for the sky, the building and surroundings, and the internal lights. A typical processed image in fact will be a composite of 5-10 raw files.

The camera itself is very important here. I have usually got my best images with the Canon 5DS-R. The sensor with this camera has three particular strengths. It lacks  a low-pass filter, which renders detail sharper than on most sensors. And it has a high dynamic range, and very little noise on long exposures. 

Having a sturdy tripod is important too. I use a Manfrotto 190, combined with a geared head for accurate composition. And of course, a sturdy tripod is no use if it isn't on solid ground for long exposures!