What does Heavy Fortifications do in AoE3?

Gives: Star Fort; Gives: Frontier Outpost; Gives: Fortified Outpost; Gives: Frontier Blockhouse. The game says: "Grants free improvements that increase the combat ability of Walls, Outposts, Blockhouses, Forts, War Huts, and Nobles' Huts."

Home City card

Heavy Fortifications

Heavy Fortifications (tech ID HCHeavyFortificationsUS) is a Home City card in AoE3: Definitive Edition 100.19.18309, in the decks of 2 civilizations, sent from the Industrial Age. Effect: Gives: Star Fort; Gives: Frontier Outpost; Gives: Fortified Outpost; Gives: Frontier Blockhouse.

Quick answers (3)

Which civilizations have the Heavy Fortifications card?: United States and Mexicans.
What does Heavy Fortifications do in AoE3?: Gives: Star Fort; Gives: Frontier Outpost; Gives: Fortified Outpost; Gives: Frontier Blockhouse. The game says: "Grants free improvements that increase the combat ability of Walls, Outposts, Blockhouses, Forts, War Huts, and Nobles' Huts."
What is the tech ID of Heavy Fortifications?: HCHeavyFortificationsUS.

Grants free improvements that increase the combat ability of Walls, Outposts, Blockhouses, Forts, War Huts, and Nobles' Huts.

What it does

Gives: Star Fort
Gives: Frontier Outpost
Gives: Fortified Outpost
Gives: Frontier Blockhouse
Gives: Fortified Blockhouse
Gives: Revetment
Gives: Redoubts
Gives: Heavy Fixed Guns

Cost: 1250
Sent from: IV
Times it can be sent: 1
Game ID: HCHeavyFortificationsUS

In these decks

United StatesIV×1

MexicansIV×1

Source: techtreey.xml and the Home City files, AoE3: DE 100.19.18309 (build 25040513).