The Bayon temple has been subject to major work by the Japanese Government Team for Safeguarding Angkor (JASA), UNESCO and the Apsara Authority. The work started in 2005 and will end in April 2010. One of the major problems with the Bayon was that the drainage channels had been blocked. This caused water damage and subsidence to the structure. The southern library was also in very poor condition and near collapse. It needed to be partially dismantled and rebuilt. Major problems with the 41-metre high central tower were identified by extensive measurement and monitoring. The structure could have become Cambodia's Leaning Tower of Pisa without the efforts of JASA. The NGO closed off the area for most of 2008 to carry out work. Visitors will notice measurement gauges and new timber supports to the underside of parts of the tower that recently reopened. The Bayon is sporting new thatched roofs to protect the northern bas reliefs, which are under repair. The thatch looks so much nicer than blue plastic tarpaulins, and are more ecologically friendly too. The JASA Bayon exhibition hut near the north entrance provides information about the restoration.