Where can I extend my 60-day tourist visa in Thailand for an additional 30 days?

To extend your 60-day tourist visa for an additional 30 days, you should visit the immigration office that corresponds to the province where you are staying. If you are in Bangkok, the relevant office is located at Chaeng Watthana, specifically within the Government Complex building. Additionally, be aware that it is not directly on Changwattana Road, so transportation arrangements like a taxi or motorcycle are necessary to access it from the main road.