Old Town is directly accessible from two out of Prague’s three metro lines. Line A (green) runs directly through the middle of Old Town, while line B runs approximately along the Old Town’s south-eastern border.
Technically there is only one metro station directly in the Old Town (Staromestska on line A), but there are three other stations just off its border which you can use to reach the Old Town: Namesti Republiky (line B), Mustek (both A and B, but see notes below), and Narodni Trida (B). You can find more details below, including which station is best for which places and what to watch out for.
Staromestska Station
Staromestska is actually named after Old Town (Stare mesto in Czech) and it is the closest metro station to Old Town Square, Charles Bridge, Jewish Quarter, and a number of other attractions. It is situated in Kaprova Street, which is the street that links Old Town Square and Franz Kafka Square on one end with Jan Palach Square (Namesti Jana Palacha) and Manes Bridge (Manesuv most) on the other. The metro station is a bit closer to Jan Palach end of the street, where you can also transfer to trams. It is still very close to Old Town Square though (some 300 metres).
Mustek Station
Mustek is the intersection of metro lines A and B and therefore one of the busiest stations in all of Prague. It is located at the bottom end of Wenceslas Square – the place where this square meets the big shopping street Na Prikope and where Old Town begins. The name Mustek actually means “little bridge” and hints at a former border of the Medieval city. It is only some 350-400 metres’ walk from Mustek station exit to Astronomical Clock and Old Town Square.
That said, when exiting the metro at Mustek, make sure you exit to the right end of the station. The various exits are scattered over a relatively large area, so you might as well end up in the middle of Wenceslas Square, which is additional 300 metres away (the “square” is huge, it’s actually more like a long wide boulevard). After you get off a metro train, follow the signs for Stare mesto / Old Town, Na Prikope or Na Mustku (the latter is the small street leading towards Old Town Square).
Namesti Republiky Station
Namesti Republiky station is on line B between Mustek and Florenc (central bus station and interchange to line C). It is situated at a square with the same name, which means Republic Square. This station is best for reaching the eastern part of Old Town, including Celetna Street, Powder Gate, Municipal House, or Tyn Church. There are two big shopping centres at Namesti Republiky – the bigger and newer Palladium Mall and the older and smaller Kotva. Just behind Kotva there is Prague Stock Exchange and on the other side of the square there is the characteristic building of Czech National Bank. This area is where the tourist Prague (Old Town) meets the contemporary, business Prague. It is about 6-8 minutes’ walk from Republic Square to Old Town Square (either via Celetna Street or via Tyn).
Like Mustek, Namesti Republiky station has exits on both ends and it’s better to exit towards Namesti Republiky – the square itself. The other exit goes to Masaryk Train Station (Masarykovo nadrazi), where big hotels like Marriott or Hilton Prague Old Town are located (the place is not really Old Town, though close).
Narodni Trida Station
Last of the four Old Town stations is Narodni Trida (National Avenue), named after a street which links the National Theatre at the riverbank with Jungmann Square. This metro station is best for reaching the southern end of Old Town, which may be a bit less popular with foreign tourists than some of the other parts, but includes a number of theatres, bars, museums and churches. The best known landmark in this area is probably the Bethlehem Chapel.
Narodni Trida station becomes more important at night when the metro stops operating, as it is the main intersection of night tram lines (mainly Lazarska tram stop, which is just around the corner from the metro station).
Access to Old Town from Metro Line C
The third of Prague’s underground lines does not go through or immediately close to Old Town, but it is not that far away. If you stay somewhere on line C, you can get to Old Town by transferring to line A at Muzeum station or to line B at Florenc, but you may as well walk.
Muzeum station is directly at the upper end of Wenceslas Square, so you just need to cross this square (about 10 minutes and all slightly downhill) to get to the border of Old Town.
Alternatively, you can get off the metro at Hlavni Nadrazi (central train station) and walk through Jeruzalemska Street. After less than 5 minutes you cross tram tracks and get to the building of Czech National Bank (from behind). You can take the passage through this building to get to the Municipal House and Powder Gate, where Old Town starts. This is usually as fast or faster than transferring to line A or B only for one more metro stop. The metro in Prague city centre is quite deep and it takes a long time to enter and exit the platforms.