A company that crowdsources the finances, buys the abandoned real estate, rebuilts it and splits the earnings among the people who helped to finance it.
As previously mentioned, abandoned real estate can be a huge burden to society. Abandoned offices, warehouses, apartment buildings, etc. could be restored, but legal issues and the prices of the buying and restoration are often autonomous.
A company would look for such real estate, create detailed investment and restauration plans and post them as an idea on the online platform. For each idea, a specific number of shares would be set. People who like the idea could buy shares online and support the project. When all the shares are sold, the company would start the investment and the building. When the building is finished, the real estate would be rented as apartments or offices for at least 10 years. All the renting earnings (except a small company fee) would be divided among the shareholders. Also, all the decisions regarding additional investments, repairs and other problems would be brought by shareholders through online voting. Shareholders could always sell the shares to other shareholders. Only after 10 years, the shareholders could decide to sell the real state to a third party and share the earnings among themselves.