Amazing Tardis art made by Helly (source)
Over the years the TARDIS interior has changed, sometimes only slightly. The original interior only had 1 level and was lighter inside. The layout remained the same throughout the classic series. The only major change was on season 14.
The last 3 versions of the TARDIS have been a lot darker and bigger than the original design.
The First Doctor in the Tardis, which the Second Doctor used too
The Third Doctor in his Tardis
The Fourth Doctor
Inside the Tardis Of The Fifth Doctor
The Sixth Doctor (used by the Seventh Doctor)
The Eight Doctor in his Tardis
The Tardis used by the Ninth and Tenth Doctor
The Eleventh Doctor’s fabulous version