Thai authorities say Chiang Mai's old city walls and seven key temples are over 90% ready for the ICOMOS evaluation visit from 3 to 8 August 2026. The UNESCO World Heritage Committee would consider the bid next year; if approved, Chiang Mai Lanna would be Thailand's 10th World Heritage site. For a Chiang Mai business, the near-term effect is on the old city: expect tidying and cleanup around the temples during the visit, and possible tourism upside from the designation later. No action is required yet.