Demolition from the ground up

As found at Gizmodo

When the P&O building was constructed in 1965, each floor was hung from a huge beam at the top of the tower and supported by the central core. According to Matthew White, project director, the weight has to be removed from the structure from the bottom up. "Eventually the beam will be deconstructed at roof level, leaving the core, which will be demolished from the top down."