From The Heroes of Might and Magic III wiki

Graveyard

The Graveyard is the level two dwelling of the Necropolis town. It produces Walking dead at a rate of 8 a week.

Requires: Fort, Cursed Temple

Cost: 1000 Gold and 5 Ore

Upgraded Graveyard

The upgraded Graveyard allows the production of Zombies.

Requires: Fort, Cursed Temple and Graveyard

Cost: 1000 Gold, 5 Wood and 5 Ore

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