This most dramatic and enchanting of Inca citadels, suspended on an extravagantly terraced saddle between two prominent peaks, is believed to be in danger of collapse. The original Inca inhabitants temporarily stabilized the mountainside, transforming some of the geological faults into drainage channels. They also joined many of the construction stones together, using elaborate multi-angled techniques, making them more resistant to both tremors and landslides. Nevertheless, these spots remain weak and significant damage can be seen on nearby buildings. The National Institute of Culture, which administers Machu Picchu, acknowledges the problems, but correcting them is an ongoing process.