Leeds and its surrounding region is the only area where back-to-back houses still exist in large numbers, having been refurbished to include "mod cons" such as indoor bathrooms and central heating. These modernised back-to-backs are popular with residents because they are easier to maintain than typical houses. The houses have proved to be popular with buy to let investors, who helped to increase prices significantly during the early-mid 2000s. The house style is also popular among student populations, as little exterior maintenance is required and they are often close to universities and colleges, particularly in the areas of Headingley, Burley and Kirkstall.