Let $(X,d)$ be a metric space and $(\bar{X},\bar{d})$ its completion. There is a list of topological properties [Wikipedia - Topological property][1] Does anybody know list which of them are retained (inherited) for completion? For example 1. if $(X,d)$ is locally compact space then $\bar{X}$ may be non-locally compact space.(Consider the induced path metric space on the following subset of the Euclidean plane: $(0,1]\times \{0\} \cup (0,1] \times \{1\} \cup \bigcup_{n=1}^{\infty} \{1/n\} \times [0,1]$.) 2. if $(X,d)$ is separable space then $\bar{X}$ is separable space. 3. if $(X,d)$ is connected space then $\bar{X}$ is connected space. 4. if $(X,d)$ is path-connected space then $\bar{X}$ may be non path-connected space. (consider the graph of $sin(1/x)$ in the plane for positive $x$. ) I am interested in this problem in general, especially for the spaces with intrinsic metric. [1]: http://en.wikipedia.org/wiki/Topological_property