Fort

Forts are super-strong defensive structures, and are also used to train a variety of units. Captains, spies, and elite cavalry units - most notably light Chariots and high-level elite infantry - are all raised from the Keep. In addition, they have a Border push effect, increasing the size of your territory.

The Fort is available for construction once Level 3 Military (Military Tradition) is researched, and with further fortification upgrades, you can improve their ability to increase your borders and their defensive capabilities, making them very impressive indeed.

Note, however, that despite being strong, Keeps are vulnerable to siege weapons, slingers and swordsmen. Slingers, while weak, can be deadly if amassed together. Sword and axe units, with their ability to damage buildings more, are also of a problem as are Battering Rams. If you are facing the Assyrian faction, then be prepared, for they are capable of raising Armoured Rams, which can make short work of your buildings. Thus, while Keeps are ideal for taking and holding ground, they should never be expected to hold out alone, especially against superior numbers. Because Keeps must be built only within the vicinity of cities, fortifying your position with them becomes a struggle, especially if you are playing a faction that does not get the Fort — only fairly developed nations like the Shang or the Egyptians can build Forts, the rest have to make do with Keeps instead.

Keep

A Keep is a more powerful version of the Fort, and is in effect a separate building. Unlike Forts, a Keep however must always be built within the vicinity of a settlement, and is also used for training and housing mercenaries. However, only factions that research Authority early on will be able to access Keeps and their special units.

Units trained

• Captain
• Spy

Upgrades

Fortification 

Without Fortification upgrades, Castles will well fall foul of enemy siege units. Fortification upgrades enhance a fort's tactical capabilities as well as its effects on your borders.

Notes:

• Level 1 is blocked in Rise of Ancients to Choson, Malays, Bantu, Belgae, Chavin, Germans, Nahua, and Xiongnu, Iranians
• Level 2: Zhou, Indians, Missisipians, Haudenousaunee, Olmec, Nubians, Gauls
• Level 3: Maedia, Greeks, Etruscans, Phoenicians

NAME	GENERAL INFO	COST	LEADS TO
Earthworks	"Make a ramp and let it be set in its place!" —Hattusili I, Hittite king Prereqs: [2] Increases effect of Forts on national borders to +4 +1 range for Forts +5 garrison capacity for Forts and Towers +2 line of sight for Forts	Resource cost: 100 ; 100 Prereqs: Heroic Age Level 3: Military Tradition
Crennelation	Grooves cut into walls allow for oversight and retaliatory fire by archers on the ramparts, whilst keeping them safe from enemy missiles fired in anger. Prereqs:   Increases effect of Forts on national borders to +6 +2 range for Forts +5 garrison capacity for Forts and Towers +4 line of sight for Forts Unlocks Warriors' Hall	230 ; 70
Defensive Architecture	"How happy are those whose walls already rise!" —Virgil Prereqs:   Increases effect of Forts on national borders to +9 +3 range for Forts +5 garrison capacity for Forts and Towers +6 line of sight for Forts	450; 150

Strategy

Strategy upgrades enhance the reliability of spies, and are also required for the creation of Captains.

Note that the last tier, Intelligence, is very exclusive in Rise of the Ancients - not everyone can unlock it.

NAME	GENERAL INFO	COST	LEADS TO
Non- Commissioned Officers	"Some one, it may be, old or young, can offer us better counsel which I shall rejoice to hear." —The Iliad Prereqs: Unlocks Warrior Hall -50% production time for Captains and Spies Increased LOS, Range, Speed, Hitpoints for Captains and Spies. Captain armor bonus increased to level 1.	80; 80 Time to complete: Fast
Chargés d'Affaires	"Humble words and increased preparations are signs that the enemy is about to advance. Violent language and driving forward as if to the attack are signs that he will retreat." —Sun Zi, Chinese military strategist Prereqs: Unlocks Mercenary Quarters +50% Craft recover for Captains and Spies. Increased LOS, Range, Speed, Hitpoints for Captains and Spies. Captain armor bonus increased to level 1.	150; 150 Time to complete: Rather fast
Intelligence	"A good diplomat always looks to the future. As it happens, your future is fairly easy to predict." —Christian Jacq, The Temple of a Million Years Prereqs: Advanced tech level and units -50% Captain and Spy resource cost. Increased LOS, Range, Speed, Hitpoints for Captains and Spies. Captain armor bonus increased to level 3.	300; 300 Time to complete: Rather fast Defensive Architecture