Where is it not hot in summer and not cold in winter, and it is clean to avoid radiation and pollution?

I don't think there is such a place on earth. If so, it may be in heaven. America has Doomsday Castle. The doomsday castle was built thousands of meters underground. Radiation protection, bomb prevention, power system, constant temperature system, ventilation and water purification equipment. Enclosed in it, it can be built for three to five years, and such a doomsday castle costs more than100000 dollars.