Original name given to the White City of Gondor
'Tower of the Sun'

Finrod's First Age tower upon Tol Sirion eventually captured by Sauron
'Tower of Guard'

Isildur's fortress upon the Ephel Duath
'Tower of the Moon'

Fortress of Gondor captured by the Witch-king in TA 2002
'Tower of Dark Sorcery'

Melkor's fortress beneath Thangorodrim in the First Age
'Hells of Iron'

Capital fortress of Fingolfin upon the Ered Wethrin at the source of the River Sirion

First Age tower of Finrod built to guard the sea against a naval attack from Morgoth
'Tower of the White Horn'

Mighty stronghold of Sauron during the 2nd and 3rd ages
'Dark Tower'

Northern citadel of the Dwarves of the First Age
'Great Fortress'

Twin guardians of Mordor upon either side of the Morannon originally built to keep servants of Sauron out, but eventually fell into hands of Sauron himself
Narchost & Carchost

Lair of the Necromancer in southern Mirkwood
'Hill of Magic'

The Valinorian stronghold of Feanor where Morgoth stole the Silmarils and killed Finwe

Castle that guarded the entrance to Helm's Deep

Finrod's hidden, underground fortress on the River Narog

Gondorian tower within Isengard inhabited by Saruman at the time of the War of the Ring
'Cunning Mind' or 'Mount Fang'

Ancient tower of Arnor built upon Weathertop
'Hill of the Wind'

Originally a watchtower of Gondor, was captured by Sauron and was later site of Frodo's imprisonment by orcs
'Pass of the Spider'

Melkor's ancient northern fortrees, delved in the time of the Lamps and destroyed by the Valar at the awakening of the Elves
'Underworld'

Originally known as Minas Tirith, Sauron's fortress where Finrod saved Beren's life during the Quest for the Silmaril
'Isle of Werewolves'

The ancient city of the Kings of Arthedain
'North Fortress of the Kings'

Ancient capital of the kingdom of Arnor founded by Elendil on the shores of Lake Nenuial
'West-tower'

Hidden city of Turgon protected by the Encircling Mountains
'Hidden Rock'

Stronghold of Thingol in Doriath
'The Thousand Caves'

The royal city of Numenor

Brithombar and Eglarest, the havens of Cirdan in Beleriand

The southern citadel of the Dwarves of the First Age in the Blue Mountains
'Dwarf-dwelling'

The tree-city of Celeborn and Galadriel in Lorien
'Fortress of Trees'

Ancient capital of Gondor that lay in ruins at the time of the War of the Ring
'Fortress of the Stars'

The chief city of Rohan and seat of its king
'The Courts'

Stronghold sacked by Smaug and refounded by Thorin
'Lonely Mountain'

Ancient mansion of Durin and source of mithril; attempted recolonization by Balin ultimately failed
'Dwarf-mansions'

Great haven of the Numenoreans to the south of Gondor where Ar-Pharazon landed with his mighty fleet

The city of the Valar where nearby grew the Two Trees of Valinor

The city of the Elves of Aman upon the hill of Tuna

The haven of the Teleri on the eastern shores of Aman and site of the Kinslaying
'Haven of the Swans'

City of the Elves of Eregion where Celebrimbor forged the Rings of Power

Havens of Cirdan from which Elves set sail into the West in the later Ages
'Grey Havens'

A township on the shores of the Long Lake
'Lake-town'

Most ancient of the havens of Gondor upon the Anduin where Aragorn intercepted the fleet of Corsairs
'Garth of Royal Ships'

Haven of Elrond known to Men as Rivendell
'Ravine Valley'

The fenced home of Radagast on the edge of Mirkwood