In Falskaar, a courtyard exists for the ruin: however, the portal cannot be used after it is used to come from the Echo Deep Mine.
Nobody knows when the portal was created or when the Dwemer settled in Falskaar. What is known is that the portal itself refers to an ancient prophecy foretold many years ago when the Heart of the Gods was used to make the island habitable. That prophecy stated that the person who travelled through the portal in Mzubthand would mark the beginning of the worst and that person would be denoted "The Traveler".
Based on this, it can be assumed the portal was made before the prophecy was created, but it is unknown how the lexicon that powers it was hidden and concealed for all that time.