Heritage is the set of assets that something or someone inherits.
When we say it is cultural it is because it regards culture itself. Culture can be a set of lifestyles, customs, knowledge and many other things.
Some cultural assets can consist of: monumental architecture, works of art, military and defensive architecture, witnesses at work and witnesses to agricultural culture.
Preservation is a part of cultural heritage, is a method and the idea of keeping the value of cultural identity.
Maintenance is part of preservation, it is an operation to maintain, upkeep and keep a building in full working order. Maintenance is also a way to ensure the inhabitants of a building are always safe from the building itself.