There is a funny thing about building implosions. On the one hand we have a group of architects and engineers who originally designed a building to stay standing, even in the case of catastrophic events like hurricanes, fires, and earthquakes (hence modern innovations such as earthquake safe buildings). With a building implosion, another set of engineers must defeat all of that hard work and bring the structure down as efficiently and safely as possible. The goal is for the building to fall straight down and land in a pile roughly the size of the building's foundation. So how do they do it? Initial efforts were crude — massive explosions levelled the building, as in the 1773 destruction of Holy Trinity Cathedral in Waterford, Ireland. Today, this simplistic approach is frowned on because large explosions cause collateral damage to other nearby buildings. In a modern building implosion, some of the exterior of the original building will be removed manually because it has value. Remaining exterior walls may be perforated or removed entirely. Interior structural beans that keep the building standing will be exposed. And this is where the real engineering comes in. The easiest thing would be to simply cut all the beams and let the building fall. However, this approach is unsafe and would probably, because of the timing, cause the building to fall over rather than collapse in a pile. Instead, engineers carefully analyse the structure and the loads to understand how the building needs to collapse. Some of the beams are partially cut to weaken them. Then explosives are attached to the columns at carefully calibrated positions. The explosives are called "shaped charges, which focus the explosive force in specific directions. The effect is to cut the steel support beams precisely where required. The shaped charges also reduce the total amount of explosives needed. This is important to demolition engineers because large explosions can damage adjacent buildings and infrastructure, for example by breaking windows. Once all of the charges are set, they are wired back to a controller. The explosions throughout the building are carefully ordered and timed so that they occur in the correct sequence. Gravity does the rest and the building collapses.