U.S. and U.K. passports - the most powerful in the world

According to ranking from Arton Capital, holders of American and British passports sport the most powerful passports in the world. The ranking is based on the number of countries where passport holders can travel visa-free or visa-on-arrival. Via CNN Money, here's the most and least powerful with number of visa-free countries in parentheses. 

The top of the heap:

• U.S., U.K. (147 countries)
• France, South Korea, Germany (145)
• Sweden, Italy (144)
• Denmark, Singapore, Finland, Japan, Luxembourg, Netherlands (143)
• Switzerland (142)

Bottom of the power pile:

• Congo (Dem. Rep.), Yemen, Central African Republic, Kosovo (41)
• Equatorial Guinea, Bhutan, Comoros, Burundi (40)
• Somalia, Eritrea (39)
• Afghanistan, Djibouti, Iraq, Ethiopia, Nepal (38)
• South Sudan, Solomon Islands, Palestinian Territories, Sao Tome and Principe, Myanmar (28)