With its emphasis on all things visual, Tumblr has emerged as one of the most engaging platforms for observing architecture, ranging from the historic to the surreal. The upload-based social network is a haven for image-hoarders everywhere, with each Tumblr carefully curated to indulge a very specific craving, be it endangered Brutalism or decadent interior design.
For architectural history fanatics, Tumblr has proven an unending boon. It hosts thousands of images with historical documentation, and takes the role that a library or archive might have 50 years ago. Other feed-based networks fulfil other needs of the architectural community, forum, event calendar, yearbook, etc, but Tumblr peddles in images.

Source: The 20 Best Architecture Tumblrs