Is it true that one Ramadan in Medina is equivalent to seventy Ramadans elsewhere?

The gist of the answer is: There is no sound hadith indicating that fasting Ramadan in Medina is equivalent to fasting a thousand months or seventy months elsewhere. Such hadiths are weak or fabricated. As for fasting Ramadan in Mecca, a very weak (maudu') hadith has been reported concerning it, suggesting a multiplication of reward. Good deeds are multiplied in virtuous places and times, such as Ramadan and the Two Holy Sanctuaries, without specifying a particular number for this multiplication, except for what has been reported regarding the virtue of prayer in the Sacred Mosque and the Prophet's Mosque.