Marienplatz
Since the city's earliest days, the Marienplatz has rated as Munich's central square and the city's focal hub.  Today it remains full of life and is often the scene of all sorts of special events.  You can reach Marienplatz on foot in about 15 minutes from the main station, and get the underground from here straight to the Allianz Arena.
 
Neues Rathaus
The square it is dominated by the neo-Gothic 'Neues Rathaus' or 'new town hall', built between 1867 and 1908 (the old one is also on one side of the square). 

Marienplatz and Neues Rathaus

 
Glockenspiel
Tourists gather on Marienplatz every day to watch the characters of the Glockenspiel on front of the Neues Rathaus do their stuff as the clock strikes 11am and 12 noon (at 5pm too from March to the end of October).
 
Town hall tower
You can also get a good view around Munich from 85 metres up in the Rathaus tower.

Marienplatz - Frauenkirche in background

 
Tower opening times
The tower is open Nov-Apr, Mon-Thur 9am-4pm, Fri 9am-1pm, closed Sat, Sun and public holidays; May-Oct, open Mon-Fri 9am-7pm, Sat-Sun and public holidays 10am-7pm).

Ratskeller restaurant
As in the Rathaus in many German towns there is also a good restaurant in the basement of the Rathaus in Munich, the 'Ratskeller'.

The Ratskeller website
(a bit of this site is in English)

Door to the Ratskeller restaurant