"New york", "Atlanta", "Mumbai"
"Beijing", "Paris", "Budapest"
"Brussels", "Oslo", "Singapore"

New york Atlanta
Beijing Paris Budapest
Brussels Oslo Singapore

>>> df
          0        1          2
0  New york  Atlanta     Mumbai
1   Beijing    Paris   Budapest
2  Brussels     Oslo  Singapore

>>> df.apply(" ".join, axis=1)
0    New york Atlanta Mumbai
1     Beijing Paris Budapest
2    Brussels Oslo Singapore
dtype: object

>>> df.apply(" ".join, axis=0)
0    New york Beijing Brussels
1           Atlanta Paris Oslo
2    Mumbai Budapest Singapore
dtype: object

df[0].str.cat(df.ix[:, 1:].T.values, sep=' ')

0    New york Atlanta Mumbai
1     Beijing Paris Budapest
2    Brussels Oslo Singapore
Name: 0, dtype: object

%timeit df.apply(" ".join, axis=1)
10 loops, best of 3: 112 ms per loop

%timeit df[0].str.cat(df.ix[:, 1:].T.values, sep=' ')
100 loops, best of 3: 4.48 ms per loop