They have filled in lots of nooks and crannies over the yrs on campus, but I truly hope they never encroach on central campus. It is a treasure. IMO
Whether central campus has been encroached upon depends on your time reference and your definition of 'central campus'.
Starting at the northwest corner of Osborn and Morrill Road several large trees were cut down to build an auditorium between LeBaron and MacKay Halls.
On the northeast side of 'central campus' Troxel Hall was built just north of the Farm House and Jischke Honors to the west of the Farm House.
On the southeast side of 'central campus' many trees were cut down to build the Gerdin Business Building.
Going back further in time (1960's to early 1970's) on the southwest side of 'central campus' Carver Hall and the Music Building were built. However, I'm not sure if those two replaced earlier buildings or were 'new buildings' occupying formerly green space. That was before my time.
Now some new 'green space' has been created over the years like the west quad; located between Parks Library and Enrollment Services. That used to be parking lots and some Quonset huts.
But other green space has disappeared. The 'block of buildings' north of Beyer Hall used to be all green space. I believe the football team practiced there when Clyde Williams Field was the football stadium. Now you have Howe and Sukup Halls plus College of Design and Town Engineering in that space.
I recall seeing a planning document that proposed a 'north quad' to be located in the parking lots behind the Molecular Biology Building and Metals Development Building and Advanced Teaching and Research Buildings. That idea has never moved beyond a paper planning document.
One thing I would like to see is Morrill Road to extend north from Osborn Drive past Pammel Drive and then under the railroad tracks to the old west Pammel Quonset Hut village and curving east to meet up with Hawthorne Court Drive. Morrill Drive would then cross in the middle of the proposed north quad.
I would also like to see the campus acquire the blocks between Sheldon Ave and Hyland north of Lincoln Way.