If you have only two days for exploring Prague, then concentrate the Old Town, the Lesser Town on the Castle District.
Walk to the Old Town Square, view the ‘must see’ Astronomical Clock and visit the beautiful Gothic Church of Our Lady Before Tyn and the baroque Church of St Nicholas. From there, head to the Charles Bridge and take some beautiful photos. Next, climb up to the imposing Prague Castle, where St Vitus Cathedral, the Golden Lane and the Royal Garden await. If you are tired of walking, you might take a tram up the hill and walk to the castle from the other side. When you get hungry, make your way back to Malostranske square and have a traditional Czech meal at one of the numerous pubs and restaurants.
The second day is good for ‘laid back’ exploring or a leisurely walk along the river. From the Old Town Square walk to the Josefov, visit the Jewish museum, have a coffee at Slavia Café or at the Imperial Café. In the afternoon do some shopping around Wenceslas Square. In the evening you could have a few pints of world famous Czech beer at the Golden Tiger pub, or if you like classical music you might attend a concert at the Rudolfinum.