He is referring to http://www.imperial-library.info/content/tower Here is another link about http://www.imperial-library.info/content/facts-and-opinions-nu-hatta-intercept
After a closer look, the second link is quite good.
So the towers are
(my remarks in italic):
Mundus was given a second Tower at this time, Red Mountain with the Heart of the World [Heart of Lorkhan](Morrowind, TES3).
The witnesses to these events [Aldmer] built more towers: White-Gold [The White-Gold Tower] (Cyrodil, TES4), Crystal-like-Law [The Crystal Tower](Summerset Iles), Orichalc [?], Green-Sap [Falinesti?](Valenwood), Walk-Brass [Anumidium](Daggerfall, TES2), Snow Throat [Throat of the World](Skyrim, TES5), et cetera. Oblivion first troubled the Mundus at this point.
Someone earlier said something about each tower being empowered by a stone, what are these?
For Numidium its probably the Mantella.
For the Red Mountain it was the heart of Lorkhan.
For the White-Gold tower it was the Amulet of Kings.
For the Throat of the World... we will see.