[Mänwe]

I believe the quote that Rune and The Might are referring to is the following from the Silmarillion;

“It is said that the towers of Emyn Beraid were not built indeed by the Exiles of Númenor, but were raised by Gil-galad for Elendil, his friend; and the Seeing Stone of Emyn Beraid was set in Elostirion, the tallest of the towers.” – (Of the Rings of Power and the Third Age, Silmarillion)

“towers of” therefore includes all those on the Emyn Beraid, however there is a quote earlier that states;

“Elendil was cast up by the waves in the land of Lindon, and he was befriended by Gil-galad. Thence he passed up the River Lhûn, and beyond Ered Luin he established his realm, and his people dwelt in many places in Eriador about the courses of the Lhûn and the Baranduin; but his chief city was at Annúminas beside the water of Lake Nenuial. At Fornost upon the North Downs also the Númenóreans dwelt, and in Cardolan, and in the hills of Rhudaur; and towers they raised upon Emyn Beraid and upon Amon Sûl;” - (Of the Rings of Power and the Third Age, Silmarillion)

So could the later quote be referring to elf built towers, different from those raised by Elendil’s people or as I highlighted, “towers of Emyn Beraid” means all those on and around the Tower Hills?

The dream that The Might has quoted was a much ‘pruned’ version of three drafts written by Tolkien, where Gandalf is imprisoned in Elostirion. In ‘The Treason of Isengard’ HoME Vol VII in ‘Chapter V: 'A Conspiracy Unmasked’ (with 'The Dream of the Tower'). However we know that the truth of Gandalf’s delay is because of his imprisonment in Orthanc, which Frodo also dreams about.