what experiment did niels bohr conduct, and became famous for?

N. Bohr....

Bohr really didn't do any actual experiments.  The wavelengths of the lines in the emission spectrum of hydrogen were well established, but unexplained.  The lines in the Balmer series were well known.  Balmer had only an empirical equation to predict the wavelengths, but no physical explanation.

Bohr was a theoretical physicist and took the existing data and developed an explanation which was based in part on the quantum theory of Max Planck (1900).  Bohr's 1913 paper explained how electrons must exist in only allowed energy levels and energy was either absorbed or emitted as electrons moved from from one allowed state to another. 

We know that Bohr's explanation was very incomplete, and only worked for hydrogen (or other 1-electron atoms).  But it was important to the further development of atomic theory and quantum mechanics.  This is why it is given a historical treatment early in the chemistry curriculum.  But it is important to know that the Bohr model should NOT be taken as something which is useful today.

Any experimentation can be done in 20 minutes.  My students do it every semester.  They measure the wavelengths of the Balmer series for hydrogen.  Then they use the Bohr model to predict the wavelengths and compare the two.  They compare nicely.  That's because the Bohr model only works for hydrogen.

Here's the photo I made of the hydrogen spectrum using our spectroscope. (The scale shows nanometers x 100.)

Electron sublevels were disproved by quantum physics. the Bohr model is obsolete.