I want to create a new DataFrame from another for rows that meet a condition such as:

uk_cities_df['location'] = cities_df['El Tarter'].where(cities_df['AD'] == 'GB')
uk_cities_df[:5]

but the resulting uk_cities_df is returning NaN.

The csv file that I am needing to extract from has no headers so it used the first row values for such. I need to only include rows in uk_cities_df include the ISO code "GB" so "El Tarter" denotes the values for location and "AD" for iso code.