UMH (or the Underground Mental Hospital) is where MentalTale takes place. Its location is the entirety of the Underground; it was remodeled to an extent to house mentally ill humans and monsters. It splits up each area of the Underground, and places different patients in different areas.
The Main Lobby of UMH is Toriel's home in the Ruins.
The Courtyard is the equivalent of the Ruins, and the area where, in Undertale, the player wakes up.
Block 1 (or Area 1) was previously known as Snowdin.
Block/Area 1 was previously known as Waterfall.
Block/Area ) was previously known as Hotland.
Block/Area 4 was originally the MTT Resort.