The Stacks project

Example 5.10.4. Let $X = \{ s, \eta \} $ with open sets given by $\{ \emptyset , \{ \eta \} , \{ s, \eta \} \} $. In this case a maximal chain of irreducible closed subsets is $\{ s\} \subset \{ s, \eta \} $. Hence $\dim (X) = 1$. It is easy to generalize this example to get a $(n + 1)$-element topological space of Krull dimension $n$.