As it happens, I have two D&D groups I’m DM’ing for! One of them managed to get the deed for a rundown house (that’s infested with undead), so I started looking into old houses and building it up as I went, giving it an easy way in (if the players explored the tombs outside), some verticallity for the combat and a room for the final showdown with the necromancers.
In the end, I even had a zombie troll coming out of the ground, revealing an underground passage into a deep ruin beneath the house!
In the end, the players loved the house so much that they’ve started making plans for it, deciding who gets which room, how they’ll decorate and furnish it,
It’s so rewarding to see people enjoy it so much, it’s an amazing feeling for creators like me. x)