This undated postcard shows the Wisconsin Tower, originally known as the Mariner Building, which still stands on the northwest corner of 6th and Wisconsin.

The 22-story art-deco office tower was built in 1930. The original name came from the developer, John W. Mariner, who died a few months before the building was completed. Upon completion, it was the second tallest building in Milwaukee. The name changed to the Wisconsin Tower in 1939. The building was converted to condominiums in 2005.

Generations knew this building because the west side was used for large billboards that spanned many floors. Here is an early shot with several advertisements on the side of the building: https://www.wisconsinhistory.org/Records/Image/IM129061

You can’t see it in this postcard, but the building featured a 50-foot steel mast for a revolving beacon light and radio towers on the roof. There have been rumors that the tower was intended as mooring for blimps, but apparently there is no proof of this. The tower was originally enclosed in glass and used as an airplane beacon. You can see the tower enclosed in glass in this old photo on the MPL website: http://content.mpl.org/cdm/singleitem/collection/HstoricPho/id/1055/rec/16

The 4-story building to the left, Central Market Apartments, was built in 1918 with a grocery market on the first floor and apartments above. It still stands today.

And to the left of that are the Norman Apartments, built in 1888 and demolished by fire in 1991.

Sources:

https://en.wikipedia.org/wiki/Wisconsin_Tower

https://www.wisconsinhistory.org/Records/Property/HI41849

https://www.wisconsinhistory.org/Records/Property/HI66797

https://www.wisconsinhistory.org/Records/Property/HI111506

Identifiers:

PLUS Code: 23QJ+M7 Milwaukee, Wisconsin

Approximate Google Street View Today: https://goo.gl/maps/wFXpUtd2fetGy7Ym6