Gondor:

The South Kingdom, Gondor was founded in the year 3320 of the Second Age, by Elendil and his two sons ruled it until the War of the Last Alliance, when Elendil and Anárion were killed. Then Isildur became the High King of both kingdoms. The Kingship lasted until the year 2050 of the Third Age, when the last King died. After this the Stewards ruled in the name of the King, until the year 3019, when Aragorn took back the Kingship of both Arnor and Gondor.
Gondor had three main cities and several smaller ones. The main cities were:

Minas Anor
Minas Ithil
Osgiliath (the capital until the year 1640)

The Golden Wood:

Another name for Lothlórien.

The Glittering Caves of Aglarond:

This was the cave complex at Helm's Deep. During the Battle of Helm's Deep, Gimli was one of those who took refuge within the caves when the wall was breeched. When he saw the beauty of the natural caves, he resolved to bring his kin-folk to see them as well, calling them a marvel of the known world. Gimli was so eloquent about the caves that Legolas found himself lost for words.

After the War of the Ring, Gimli became the Lord of the Glittering Caves.

Gondolin:

The hidden city built by Turgon, Gondolin was the longest lasting of the Elven realms in Beleriand. It was built in the hidden valley of Tumladen within the Echorath. There was only one easy entrance, known as the "Way of Escape". The city was designed in memory of the city of Túna, and after time, equaled it.

The reason that Gondolin survived so long in the wars against Morgoth was that for many years nobody knew where it was. Only four people came into the city later than those who founded it. Those four were Maeglin, Eöl, Hurín and Huor. Also, Ulmo had long blessed the waters of the Sirion River.

Turgon took ten thousand of his forces to the Nirnaeth Arnoediad, revealing the existence of the city for the first time. However, the secret of the city's location remained. After the battle, Tuor was brought to Gondolin. Later Earendil was born to Idril.

The city was eventually betrayed by Maeglin, who had been captured by Morgoth. The forces sent against Gondolin included: wolves, orcs, dragons and Balrogs. The destruction was utter and complete.

The Grey Havens:

A coastal town in the Gulf of Lhûn. This was Círdan's residence from the beginning of the Second Age of the Sun until some point in the Fourth Age, when he too took ship into the West.

By some time in the Third Age, this was the point from which the vast majority of the Eldar left Middle-Earth via the Straight Road. Apparently, many had at one point left from a location near or within Gondor at some point, but by the time of the War of the Ring, unless the elf wanted to construct his own ship, the Grey Havens were their only port.

Another name for the Grey Havens was Mithlond.

The Hobbit
The Lord of the Rings
The Silmarillion
The Complete Guide to Middle-Earth by Robert Foster
The Unfinished Tales