The renowned Scottish architect William Henry Playfair was responsible for the elegant thoroughfare that encircles the hill on three sides. Comprising Royal Terrace, Carlton Terrace and Regent Terrace, the largest of the townhouses can be found on Royal Terrace. Playfair's plan is dated 1819 and the first house was built at what is now 40 Royal Terrace. Regent Gardens that cover over one half of the summit of the hill are privately administered by the local residents' association. Carlton Terrace was originally called Carlton (or Carleton) Place but changed in 1842 to fit in with the other Terraces.