Erected in 1551, the old tower on the Drava River was the largest of six that once formed Ptuj's Renaissance defence system. Originally it had no roof because it was used as a gun cannon platform. When the tower lost its original function, it was initially converted into apartments, and then in 1938 into an exhibition space. For some years a viticulture collection was displayed here, but since 1967 the space has been used for art exhibitions.
Beside solo exhibitions of regional authors such as Andrej Božič, based in Ptuj, or Polona Petek, a Maribor-based artist of the younger generation, it features also other Slovene artists like Klementina Golja. It prepares also group exhibitions as the exhibition entitled Masters [Mojstri] that in 2009 featured the work of still-active artists of the first post-war generation of the Academy of Fine Arts and Design in Ljubljana: Bogdan Borčić, Jože Ciuha, Albin Lugarič, Vladimir Makuc, and France Slana. Such exhibitions are as a rule on view at all locations of the museum which cover contemporary art production, sometimes also in the exhibition area of the Ivan Potrč Library Ptuj.
Mihelič Gallery is a co-presenter of the Art Stays, International Festival of Contemporary Art that is organised each summer by the Art Stays Cultural Association. Its exhibition is traditionally featured in August and is the most important international event of the Mihelič Gallery. In 2009 the cooperation between both organisers resulted in an exhibition of Italian Graphics, curated by Marika Vicari.