We have two threads for one topic now, but to add to the diversification vs concentration discussion. I think having 1/2 or 1/3 of one's money in a single stock is a much different proposition than having that large of a percentage in one single property.
At the risk of stating the obvious, a stock is an interest in a company which will presumably have diversification of operations within its industry across geographies or even diversification of industries.
A small piece of land with a building on it is much more susceptible to total loss in an adverse event. A single fire/tornado/flood/hurricane/environmental event/lawsuit/municipal law change can not destroy a decent sized company, but a can certainly wipe out a real estate investment.
Also a directly owned real estate investment is like owning a small business and can unexpectedly call on your liquidity and capital for a variety of reasons.
In order to compensate me for all those issues, I would need require return greater than 8% and have a net worth sizable enough to spread my risk over several properties. The question posed doesn't provide enough information to gauge as to whether or not the return would be higher.